Tbh, all of them suffer in one way or another, mostly because there are way too many characters and Oda simply doesn't have enough time for his supposedly main cast. Here's my take on the SHP:
Luffy - hate G5. Other than that Luffy is more or less the same he's been.
Zoro - seems like Oda decided to dumb him down a little. But overall Zoro is the same cool badass swordsman he's always been.
Nami - gets robbed from a fight more post-TS, but overall seems similar to pre-TS, a pretty woman with a bossy streak, sometimes a scaredy cat, sometimes a greedy one because she kinda was conditioned to that since her childhood.
Usopp - lol I even forgot to include him first. I was never a fan of his, but at his core I think he didn't change much? He's also a weak scaredy cat, but can be reliable at times? In a way, I am kinda happy to see less of him.
Sanji - my god do I hate his pervy gag turned up to 11, but since it was tuned down a little it became bearable again. Other than that Sanji feels the most like a main character, he has gotten a lot of focus and character growth. Even if I hated some of the lows for his character, the highs make up for that.
Robin - oh don't get me started. I am really disappointed to see her sidelined so much. And I really dislike the fact that she actually knows a lot and was willing to share, but stays silent because Luffy said so! Okay, Luffy doesn't wanna know, but I do! I don't see anything I can dislike Robin for post-TS, but imo she's simply lacks panel time and just keeps being "that mysterious and kinda strong" mid-hat. I hope SH will exile Imu and will stay on Elbaph for a bit, and we can see Robin's reaction to the mural and hopefully some lore reveal.
Chopper - doesn't get cool fights anymore. Other than that, he's the same merch magnet he was before.
Franky - doesn't get enough panel time. Also, I dislike Franky's new design, but character-wise? He's fine, just sidelined too much for the sake of a new shiny ally. I really hoped for more interactions between Franky and VP. We still might get it, but my hope is faint.
Brook - oh Brook actually has become one of my fav SH lately. Started in WCI, keeps delivering.
Jinbe - is really boring as a SH to me. I preferred him as a meaningful ally. But thanks to Jinbe I now don't really want a new SH anymore. For some characters it is better to stay cool within their arc and that's it.