Aside from the long-winded explanation below, the question is exactly what it says on the tin!
I'm absolutely, absolutely a fan of iChun's Morph mod, and that's what I've been using for a bit of a good while now, and I'm almost hesitant to switch to a different one for fear of losing the lil' library of creatures I can turn into... as well as the rapid-spacebar-tapping flying mechanic for the bat, because even if it's the bane of my thumbs, it feels far more aimed towards a survival world than just straight-up-creative-mode-esque-flying as a bird or a butterfly from a different mod or whatnot. Heavens. Just feels more immersive. I can't explain it beyond that.
But I'm not about to go bug them about updating it (they're as busy as heck right now), and I'm not quiiite sure I've got the time myself to try and fiddle with mod-updating. (Plus I'm sure that would come with questions I'd have to direct towards iChun about their unique code, and now the problem is riiiiiiight back to square one.)
Honestly, I'm pretty dang happy playing it as-is, but I can't keep pretending that versions of Minecraft don't exist beyond 1.12.2, and I really want to enjoy everything the game has to offer, so I suppose I've got to bring my magical little world to a new age at SOME point here, even if it means saying buhbyenow to some of the little 12.2 things I've grown to love. (And I could always ask for someone's help to make a lil mod to make any survival-flying mechanics similar to iChun's bat. Or learn to do so myself!)
So what are your folks' favorite shapeshifting mods that are up-to-date? I've heard-tell of a number of them out there, but I really like getting first-hand reviews so I can ask follow-up questions if I have any. (Although I'm probably not as picky about mods as I think I might be.)
It'd be treeemeeendously optimal if they're compatible with (or configurable towards) BetterAnimalsPlus and Mo' Creatures!