OP, I have first-hand experience with multiple R290/X from those AIBs you mentioned. Here's my quick run-down:
1) Powercolor - if you don't have any issues with your card, they are fine. If you do, they have a reputation for nickel and diming on RMA issues like fans failing. My 290X PCS+ had a fan fail and they would not replace on their dime. So I switched to an AIO CLC. Out of the box the fan curve is a little aggressive and even though the cooler IS beefier than the Tri-X I would still give the Tri-X the nod overall.
2) Sapphire Tri-X is one of the best cooled 290/X and should perform well out of the box. RMA however is a pain in the rear. They outsource their RMA to Althon Micro and it's seriously hit or miss and SLOW. Lucky for me it was just a BIOS issue and after a week of back and forth I got it fixed with a BIOS they sent me. Newer Tri-X should not have any issues (I bought the cards on release).
3) XFX has a middling cooler, but their warranty/RMA service is good. I had a fan fail on a 290 and they shipped me a replacement HSF assembly on their dime. Lifetime warranty after registration never hurts either...
4) Gigabyte will replace cards as long as their S/N checks as under warranty. Nothing special here, but I've had cards replaced by them (e.g. 280X) in the past no questions asked. So they get a pass on warranty/RMA service.
If you plan to overclock the Tri-X will handle that better than the XFX (their cooler is optimized for noise, not performance). If you plan to run stock, XFX's superior warranty/RMA service may tip the scales.
Both are quiet at stock, no OC. Sapphire has better VRM cooling.