Honestly most factions are just whack & I'm always like ... I don't want to associate with either of y'all!!
But that's part of Fallout's charm I think lmao. Everyone is at least a little bit terrible.

In general I love how the franchise mixes things, like the concept of knights and religious aspects used in a post-modern military context for the Brotherhood of Steel & while everyone including me hates Cesar's Legion, from a design standpoint I think they're so fun. They've just become a normal part of the game by now but when I first encountered them seeing Roman Empire stuff in a retro-futuristic post-apocalypse game was unexpected to say the least lmao
I've played very little of Fallout 1&2 but I know there was a Yakuza fraction too which I hope to maybe see back for if a Fallout 5 ever comes around, I think that could be very fun too.
The Enclave sucks too, but shout-out to them for ED-E <3 It & Rex where my always companions in my og NV playthrough. I love it's little battle fanfare & beeping!! So cute!!
& I'm a bit fond of New Vegas' Boomers. They're random & they're also whack but for my other OTP's Fallout AU, I headcanon one of them being from there so there's heightened interest haha... And I love their bomber jackets.