At this point, most of the non-leaked highly-requested choices are characters that I find boring (at best) or characters I dislike (at worst). Skull Kid, Dixie (I loved the idea of her being a grappler, but I'll have Incineroar for that so I don't need her anymore), Waddle Dee, Ashley, Shadow, Paper Mario, Rex and Pyra, Banjo, Shantae...I can't really get excited about any of those, lol.
Isaac, Spring Man, Chorus Kids, and Geno are cool though, despite them not being too big of personal requests for me. Always thought so. And obviously Crash would be fantastic, and so too would be DLC Waluigi. But beyond that I basically have everyone I could ever want that has a realistic shot of getting in.
At that point I'd just be hyped for certain Fire Emblem characters (Celica, Caeda, Merric, Silque, Ogma...the list goes on) and Pokémon characters (Chandelure, Decidueye, Klefki, Marowak, Castform...), or, Sakurai willing, Henry Fleming. But I think that just goes to show how good Ultimate's roster already is. The game's roster was a 10/10 at E3 and only improved from there, especially with Chrom getting in.