r9 270x vs r9 280 vs r9 280x vs r9 380

ok... this is how it works... i'll give you the facts, you can make the choice best for you

in order of "strength" (strongest to weakest) the cards are

r9-280x
r9-380 = r9-280 = GTX 960
r9-270x

understand that the r9-380/280 and gtx960 are so close to eachother in performance that it really comes down to the game you're playing and what type of overclock the individual gpu is capable of. furthermore, the r9-270x is close enough to the 3 above it there will be AMD favored titles its legitimately a better option then the gtx 960; in reality all 4 of those cards are so close in performance to each other to call one better then the other can be a stretch at times. The one card you listed that stands out from that pack of cards is the r9-280x. It's a very old gpu architecture, but it has a lot of staying power, and it's performance is quite nice, it's a beastly card, and i loved the one i used to own.

Other consideration; Energy use and Heat/Noise
Energy and heat/noise are two sides to the same coin. The more heat there is, the noisier the card as it's fans spin up to cool it down. and it's energy usage that indicates how much heat there will be. to an extent this can be mitigated with a good gpu cooler, however know that the noisiest/loudest card on this list won't ever be a match (no matter what cooler you have) for the quietest. Now, in order of loudest to quietest
r9-280x
r9-280
r9-270x
r9-380
...
...
...
gtx 960

i put some room between the 960 and others because there really isn't a competition. 90% of the time you use your pc it's fans won't even spin up. It's a card you could run almost passive, and it uses a fraction of the power the other cards use. That said, with the right cooler all of those r9 cards are pretty quiet. However, none of them are in the same league as the almost silent 960.

The driver question:
many people make the argument that nvidia drivers are better then amd drivers which makes it a bad choice to go with AMD. I would say 4 years ago, this was very true. In recent years the quality of the amd drivers has reached a point where there is almost no end user difference between the companies for the most part. That said, despite it's sterling reputation, nvidia has had a number of horrible driver releases no one speaks about, far worse then any AMD driver released in recent memory. Since June i've had more driver issues with my Nvidia gtx970 drivers then i ever had on either of my hd 7700 or r9-280x cards in the entire time i owned them. i'm sure shortly nvidia will resolve the current issues, and i don't give you that anecdote to direct you to AMD, i'm telling you this because there is a large group of fanboys on both sides who will make arguments about drivers when in truth the reality is a lot less cut and dry.

final consideration
if you asked me 3 years ago if 2gb of vram was good enough for 1080p i would have answer YES; that answer has changed with the release of the consoles. Many top end new releases require a min of 2.5gb of vram for high or better settings in 1080p; i would say now going into the future 3gb is probably the minimum needed for top setting 1080p.