Archers, Casters, and recently Berserkers love me. I used to only have 1 SSR at all for a long time (Hijikata) but now I have 3 SSR Berserkers (got lucky with summoning Raikou and Kintoki). I even have Zerkerlot and TamaCat now so I can finally field a full team of gold zerkers if I wanted to.
Most Casters except for the big supports (other than Tamamo now) like me. I’ve got Sanzang, Scheherazade, Tamamo, and some really good 4* like Helena, Circe, CasGil, and Nursery.
Archers as a class are just plentiful, which might be why I have a lot of them. I only have Gil and Moriarty for SSRs, but so many 4* like Emiya (my starter), Emiya Alter, Atalante, Helena Archer, Tristan, and Tomoe; not to mention my welfare Santa Altera.
The classes that tend to avoid me seem to be Rider and Assassin. I have no SSRs in either class. Until Shiki came along, I only had 4 gold Assassins, one of which was Stheno.
I still only have 4 gold Riders, but the two welfares (Rider Kintoki and Rider Ishtar) perform so well that together they’re almost a 5*. So performance-wise I have no issues with them.