I started playing shortly after 1.5.2 dropped back in May 2013. 1.7 was the first update I actively followed from snapshots to release. Hadn't payed much attention to it during 1.6. 1.7 added all of the new biomes and new wood types, as well as changed fishing and a whole bunch of other things. Good times. I play the most recent versions of the game, but the 2013 updates hold a special place in my heart, as those were my early days of minecraft.
This is super tough for me. Also could someone add a poll please for this to select which version of the game we prefer, thanks.
Otherwise back to answering. I'd say maybe around the 1.7.10 or 1.12.2 mostly. Even though I started in 1.4.5 a bit before 1.4.6 came out. I've jumped to 1.2.5, 1.4.7, 1.5.2, 1.6.4, 1.7.10, 1.8, 1.8.9, 1.9, 1.9.4, 1.10, 1.10.2, 1.11, 1.11.2, 1.12, 1.12.2, 1.13, 1.13.2 & 1.14 snapshot from time to time.
Obviously as a modded player mostly more than Vanilla is why I have experienced they versions so much back and forth or when they were new.
But I don't know. I'd say 1.7.10 or 1.12.2 for mods. And for Vanilla update reasons I'd say maybe... 1.6.4 maybe.
While I'm not into the 1.6 update that much, 1.4.7 and before just aren't that great for me these days to play, I use commands particularly and the way mob AI or ways of going about things prior to 1.4 just isn't great for me even after starting with it, 1.5 is ok I'd say but still feels off sometimes, and 1.7+ I hate the biomes and biome mods don't cut it for me to make it any better, but more so make it less appealing to me.
I love the content before 1.7 for biomes and otherwise how it worked out. 1.6.4 might not be the greatest update for me to run but I'd say it's the best and the one I found having the most time/fun with since I really never wanted to jump to 1.7 at all and hated it when it came out. I still hate 1.7, and most new versions updates are ok but mods are the only reason I care to play them. I don't play 1.6.4 at all these days, but if I had to say for suitability or just what I played the most and had fun with it would be 1.6.4, I do have fun now, just not as much as when I played 1.6.4 when I was still into the game then. I don't wish to go back to it at all though. I can't make up my mind XD
'Niche Community Content Finder' for fun and support of creators. I just swim through my 'Experimentation Pond' of content that intrigues me or really needs a bit of acknowledgement or bug fix testing/reporting. I also make modpacks/maps
Creator/Maintainer of Fabric, Rift & Tesla Mod Discussion Threads/Niche Mod Youtuber.