I have never updated past 1.6.4, instead writing my own mods to add whatever content that I want, which isn't much; one reason why I still play on this version is the changes to world generation in 1.7 - I can simply not play with the underground changes, which made cave systems much less dense and interconnected:
This is an underground interconnectivity map for the seed "-123775873255737467" in 1.6.4; all the green areas are directly interconnected to a single point near the origin (the area to the lower-right is interconnected to the other areas off the edge of the map):
The same seed in 1.7; this was the largest interconnected area starting from near the origin, otherwise only a cave system or two was interconnected (this does not take into account mined ores bridging across two separate caves, or dripping water/lava from the ceiling of a cave with anotehr cave just above it, both of which have lead me into (at least locally) separate networks. However, this can only reach new caves within a few blocks):
I don't like the biome generation either; I'd only see a few biomes in most of my worlds since I don't explore that much in terms of area; it takes around 6 months to fill in a single level 4 map, which is only 2048x2048 blocks (tiny by the standards of modern Minecraft, with Elytra and all):
This is a rendering of one of my modded worlds, which is slightly larger than a level 4 map in size; I played on it for about 5 months (the size includes unexplored chunks around the edges of the explored region):
An AMIDST map of the same seed in 1.7, showing mostly the same few biomes, and no deserts (hot) or snowy (cold) biomes:
There are other reasons as well; modern versions are incredibly resource-intensive to the point of being literally 10 time slower on some measures, which was particularly an issue on my older computer (1.8 went down to 1 FPS underwater, while 1.6.4 could get 100 FPS in even the most resource-demanding biomes in TMCW which put vanilla jungles to shame). Not to mention bugs, including some extremely serious ones (e.g. world corruption, there have been many reports of chunks being mislocated or regenerated since around 1.8, even more so in 1.14+), and others that I fixed myself, some a long time ago (even if Mojang has since fixed some of them that isn't a reason to want to update.
To give some idea of the number of bugs in newer versions this bug report (a bug that I fixed myself long before it was officially fixed) was made around the time 1.6 was released; the number is 17630 compared to 173148 for the newest report, so nearly 90% of all reports have been made since then. Even more, this report is for 1.13 and its number is only 125007 - 27.8% of all bug reports have been issued since then (granted, there are more players now but the number of reports has increased far faster). They couldn't even fix various rendering bugs in 1.15 (the "bugfix" update, which also rewrote the rendering engine), which I fixed and more (e.g. adding smooth lighting to water and other blocks).
Either way, even a "cave update" wouldn't make me want to play on a newer version since I've long ago modded cave generation to my liking with continued improvements since (which is certainly not like whatever Mojang might do, which might even be just adding new mobs and decorative features, sort of like 1.16 and the Nether, or 1.13 and oceans); my oldest mods are over 6 years old (TMCW was officially released on April 23, 2014 but the first world I made with it was started on March 12, 2014 and the oldest mod I made that made similar changes to cave generation dates back to September 26, 2013; prior to this I used a mod to double cave density (ironically, it was primarily intended to reduce them; it was called "Fewer Ravines Less Caves").
Well, this is by far the longest and most detailed reply I ever got on any forum/social media or anywhere else haha. I read it and I do partially agree with some parts. However, I was never really bothered by such things, except maybe bugs but luckily I never really had one so far or maybe a minor one. And I don't really find cave interconnections that big of a dealbreaker. At least not for me. But all have different opinions and I still admire your efforts and ingenuity. I like the "If I don't like the game, Imma change it" mindset! Maybe since you know so much about Minecraft and modding you could make a YT channel for mods and stuff like that if you don't have one yet. I think people would dig that!
This is a tough one for me. If I had to say modded versions it would be 1.7.10, 1.8/1.8.9, 1.10.2 (1.12.2 feels so similar but just more popular and I enjoyed it in 1.10.2 much more), but for latter 1.14.4/1.15.2. They feel gopd to play (1.7.10 a bit less so with Vanilla movement being annoying without Ctrl Sprint and earlier than 1.12.2 being annoying when 1.13+ has swimming which I use a lot). And older versions like 1.2.5 are fun but the controls for Vanilla reasons and how machines or other things work are very difficult to get used to it feels like a whole other games just to move/defeat mobs normally in those versions and also not thinking to use a shield.
For Vanilla reasons instead of modded I'm not sure. No features really stand out to me as 'best update'. Over time I've enjoyed the quality of life stuff like the Ctrl to Sprint, /locate and more and going back can feel awkward but if I had to point out things I hated it would be the 1.7.2 biomes, 1.10 was not a good update for adding anything I can remember using if I'm going off of similar updates to those listed above.
If I had to pick any that added features I use a lot I guess and think back I'd say 1.5 due to hoppers/redstone blocks, 1.6 for coal blocks as I rarely use Horses. 1.14 I love the Blast Furnace/Smoker but I feel I could go without them, even 1.13 with the treasure and 1.11 with the ocean monument/mansion maps when it comes to mods, but if I wasn't using mods I'd want them. I've thought about it when it comes to Legacy Console and how I'd have wanted 1.14 to be the last update, as 1.13 is cool and all but I use the 1.14 blocks so much.
That's just off the top of my head though. If I looked deeper besides what I use in the game that was added in particular updates and during versions I've used (regular like from 1.4.5 to 20w09a compared to alpha+ where I've tried them but not really gotten much from them as memorable updates other than expanding the game to what it is, or changing it to add hunger which I'm no fan of, just not I love the features like with other updates).
1.16 for sure. Sure, it's only snapshots BUT at the same time the Nether has needed to be updated for soooooooooo long. It's been in the game since the Alpha phase, and the generation hasn't really changed that much since the start. So I would say that my favorite is 1.16.
SuntannedDuck2 I know what you mean. All updates were good and bad for something if you ask me. There are many things that changed in the past years in Minecraft. And it's sometimes impossible to like all of the new features... for example, I didn't really like the combat update that much and also I didn't know anything about it when it first came out and then I was wondering why does it take like 15 hits to kill a horse (I was spam clicking with the sword). And then I later learned that you need to pause for a sec and then hit again.. Many features changed and I also don't like all of the changes and sometimes prefer older version's mechanics or system over new ones but I kinda just go along with it and try to enjoy the game anyway.
1.6.4 and 1.7.10 were my personal favorites. Playing creative with tons of mods like Pokemon, dirtbikes, Minecraft comes alive and many other mods just made me want to play more. The servers were full of nice people and they were very active. I don't really know why but nowadays Minecraft has changed a lot and I really don't feel like playing it. Maybe it's because of all the features they added and I can't keep up with them.
Whilst I don't have a specific update in mind I would say one of the terrain updates pre-Beta 1.17, Beta 1.7X. Alpha mountains were already epic but were taken up a notch in Beta with massive overhangs and floating bits, especially the overhangs. I found one that reminded me of an apple core once! Aside from that I would say 1.13 because of the much needed Update Aquatic, ruins and ship are fun but for me it was more about the kelp, sea grass, coral and all the fish as well as dolphins.
leangreen76 Yeah floating bits, overhangs, and all those weird mountain shapes can be interesting. Also same for me about 1.13 I love the sea and underwater wildlife in real life so I loved it in Minecraft