I've done a loooot of Gunpla but I only kept a few of my builds. I'm really mostly just a fan of the classic-ass RX78-02.
As for other kits, my old roommate used to have me put together some of those Frame Arms Girls and other such robot girl model kits (okay, I kind of volunteered) and I can't say most of them were enjoyable. Everything but the 30 Minute Sisters felt like they'd fall apart just by looking at them. The aesthetic of those kits just also isn't my personal jam.
I did a couple Digimon kits as well, which were pretty painless to put together but the materials didn't feel the greatest.
I'd like to get into doing some Evangelion kits - I did put together an Asuka that's super high quality, but ended up gifting her since what I really want are the giant robots lol. If I find one I like I'll update y'all.