Better? I'd rather say less challenging, more accessible, but also far less rewarding. More successful, no doubt. But the only sequel I spent a lot of time in was Blood Dragon.
This is the main thing that made it not fun for me, lol. There really is no point in partaking in random combat in the open-world. It's always better to run away or sneak past them. Fine in a stealth game, but FC2 didn't have great stealth mechanics beyond crouching and staying far away from enemies.
All the other FC games are stealth games too, BTW. The later FC games made it even more explicit, with bonuses for never setting off alarms and so on.
I stopped playing the series after 3 because they did feel that way, but without gameplay features I wanted to match. Games that rewarded stealth, but without stealth-specific mechanics like you'd find in Hitman or MGS. It feels like the writers want to encourage stealth but the game designers didn't. At least for 1-3. The original I definitely accepted it more because of the era.
FC2 didn't have that. FC2 was set in Africa. It's still my favourite of the bunch for a lot of reasons (only a little because I understand the local language the mooks are screaming to each other when you're in the middle of a firefight).
It's funny, when I first bought FC2 I played for about 8 hours and I hated it.
When I went back to it after about 8 years, I found that I appreciated the immersion a lot more, and it quickly became my favourite.