I think Aekold Helbrass would work well from a background perspective as his touch revived things so it would kinda work if he got revived himself.
Egrimm Van Horstmann I'd like to see cause I think it would make for a sick triple kit for Chaos. Egrimm on Baudros, Galrauch and perhaps a generic Chaos Lord on Chaos dragon.
But if I could revive anyone it would be Count Mordrek the Damned! He was like the almost Chaos spawn version of Gotrek, hoping for the sweet release of death but basically the Chaos gods didn't want him to die so he suffered mutation after mutation while retaining his sanity, which might have made things even worse for the poor sod.
I also always loved Valnir the Reaper, who also got resurrected once before by Nurgle as Papa Nurgle loved him.
I also always really liked Krell and Arbaal the Undefeated.
Oh and another dude that definitely deserves a comeback is none other than Engra Deathsword IMO. The artwork is iconic, the design splendid, he was suddenly missing after his Everchosen was slain.... there's much that could be done with him!
All of my picks are pretty darn unlikely but oh well, I hold them dear.