got back around to this thread thinking you meant 270X and I could have been more helpful.
anyway this is always a harder question to get a good answer to, because different review outlets use different methodologies and tools when measuring this stuff. best bet is when one site has done many models within a single line. as it stands, I'd say your best bet, if price is not an issue, would be either Gigabyte, Asus, or Sapphire. Tweaktown has done a lot of r9 270s. Techpowerup also did the asus r9 270.
The gigabyte card has those massive fans on its cooler so they spin nice and low.
If you're really price conscious then I have a suggestion. Right now, the cheapest of the 270s is the Club3D card. Club3d is owned by the same parent company that owns both Powercolor and VTX3D, and is based in netherlands. the brand has previously only been used in Europe. powercolor the states and Canada. I do like the look of the club3d stuff and I'm guessing that's why they're pushing it now. hardwarecanucks did a review of an r9 270. The card in question a single-fan variant from powercolor. They found it to perform exceptionally in the noise and cooling departments. Now, that card isn't sold anywhere at this time and you can't get it anymore. I remember when it came out, it was the only non-dual fan card, and then powercolor came out with a second dual-fan variant, and afterward the single fan card disappeared. most likely to respond to the competition as all their competition had dual fan variants. If you compare the Club3d cards to that single-fan powercolor card, they look similar. the fan seems to be identical and the cooler also looks very similar from what I can tell. it could very well be that the club3d cards and the old powercolor card came from the very same production line just with different shrouds affixed. if so, then the club3d cards will be quiet and cool maybe.
that said, I recently passed a club3d r9 270x, which was identical to the 270s in all but clockspeed, due to rumblings that it was noisy, and also hot sometimes. so I dunno. could be the higher clocks just defeated a cooler that performed admirably at lower ones, which was probably why they decided to push the clocks and release it as a 270X in the first place. but who knows. this is why people should send their damn cards out.
you won't be paying $50 more for a better 270, they're not that bad yet, don't give them ideas. I'd say $20 or $25 would be as hard as they could probably end up squeezing you here.