Necrons are a major winner for now. That will change imo when the meta fully changes to only have very little armor at all (if any) and we will have to see how they fare without all the new psychic powers.
I'd also like to add that Eldar don't suck as bad as people keep QQing about. I have a footdar build with ally DE for the warriors and a cheap hq and dominated my friends SW army. When I say dominate, I mean dominate. He would usually kick my balls because of the leaf blowers.
I haven't had the chance to get my Nids on the board but I am looking very forward to it. Stacking Zoans backed by a Swarmlord, yup that's the pain.
I haven't done the DW fully deepstriked tactic for a long time, and with the armor buff, I probably wont either. It does hurt that I used LR as a transport for the deathstar squad. Need to re-plan and rethink.
I feel the only real nerfs were justified or hurt only very dated codexs. Yes Eldar always scream murder because the only trick pony they learned to play for years has to be changed. No more mech, roll face with an Avatar. Trust me you'll love it.
Change is good.