Cluj is growing but it's still a bit of secondary center. Bucharest on the other hand has offices from almost every major player, I think only Facebook, Apple and Netflix are the only ones missing for now (that might change, as things are moving super fast these days). Otherwise, Microsoft, Amazon, Oracle, Google, Intel, Huawei, Adobe, SAP, etc. are there.
If you do want to move, personally I would avoid Bucharest... a bit. Competition is super fierce. Timișoara, Cluj or Iași, especially Iași, should have a decent talent pool and slightly lower salary expenses/lower cost of living, and they all have international airports so you can easily move around when needed.
I'd learn a bit of Romanian. If you only speak English it will be relatively hard, but reasonably doable: https://www.openculture.com/2017/11/a-map-showing-how-much-t... (note: those numbers are for career diplomats undergoing intensive training, however, as you can see, it's still one of the easiest languages to crack for an English speaker :-) ).