I kinda want to see Kizaru against both Luffy and Zoro (not simultaneously of course). G5 vs logia awakening would be amazing but Zoro getting to somehow make up for Sabaody could be nice especially with Saturn also in the picture as a potential Luffy opponent. Kizaru facing as many opponents as possible before going down would be ideal in my opinion. Though honestly, Luffy vs Kizaru seems the most interesting out of all potential match-ups for both combatants, Emperor vs Admiral, couldn’t ask for something more exciting and monumental.
Honestly though, I wouldn't see the issue with Zoro clashing with someone like Dobermann, would immediately elevate above some of his schmuck peers and wouldn't dehype Zoro who'd move on to bigger things like seeing how he compares to an Admiral.
As for Sanji, I'm still rooting for a fight against Lucci especially with the current situation (him leaking info, aiming for Stussy). If he also clashed against Borsalino, I wouldn't be complaining but I ain't holding my breathe. Oda did good by Sanji so far this arc, a 1v1 to completion against someone in or approaching the YC1 range would be enough in my eyes.