Like the most favourite outfit of all fandoms I've ever jumped in? That's hard, very hard.
Can I put Mire!Goji as my favourite Godzilla suit, or would it be cheating? (It's just the cutest!)
Apart from that, I can merely think of most of Aloy's Carja blazons. And another Carja outfit I found in a random chest somewhere and which's name I can't find right now.
Here be me showing it off for about half a minute: https://www.youtube.com/watch?v=S-crFzMntZk