Ubisoft - first of all I would change the way how they make games - no more design by committee which produces soulless and repetitive crap they've been churning out for so long. Then I'd put to good use their quite good open-world engines:
- GTA-esque action-adventure set in late 60s or early 70s in Europe, inspired by Italian Job (obligatory name of main protagonist is, of course, Myco Caine), with some spy things going on in parallel - London, Paris, Geneva, Monte Carlo, cool period soundtrack, fast cars and deadly Russian double agent Natasha.
- Open world action-adventure (à la RDR) or action-RPG (à la TW3) set in medieval world (fantasy or otherwise) - e.g. they've been sitting on Might & Magic IP for ages and doing nothing good with it, and if Witcher 3 is an indicator, fleshed out medieval open-world with good story is what lot of people would love to play.
- new IP (AC might work, but that IP has lot of baggage) set in Atlantis, in Richat structure (it is a stretch, but very plausible location)