There is no best brand. They all offer different warranties and different heat sinks/overclocking and different prices. I have not heard anything about palit heatsinks being bad, but that sonic platinum card you're refering too has the highest factory overclock and it has a better heat sink than stock to support it. It has a 2 year warranty. EVGA offers 4 I believe and has a buyback program if you decide to upgrade, but their cards are typically more money. MSI and Asus offer good cards as well. All these brands are pretty good, honestly I'd just buy what's on sale. The performance differences are going to be pretty small across the board.
Since I know you will get the usual MSI Cyclone or Hawk recommendations, note that the ECS Black shows load temps a full 16c lower than the Cyclone and a full 9c lower than the Hawk. For noise, it's tested at 37dB vs. 43dB for the Cyclone and Hawk at load.
Pretty much EVGA, Asus, MSI and Gigabyte are "top tier". I would call ECS,PNY and Sparkle as mid tier and then like Palit and ZOTAC as lower tier. I might be the only one who would use those ratings but that is just in my experience.
I like EVGA because of the lifetime warranty that covers me doing things like removing the heatsink and using aftermarket thermal paste.
Palit sent some "cherry picked" cards to review sites with VRAM heatsinks that did not show up on the retail versions.