RX470 Nitro+ from Sapphire. It's 8GB variant is the only RX470 with much faster 8GHz VRAM, and both 4 GB and 8Gb have proper cooling on VRAM. MSI Gaming X has the beefiest cooler overall, but I believe memory chips on it are bare. Gigabyte card shows good enough results, but overall the card is made with a bit of saving.
And Asus Strix is a special case- a badly designed card, that 'keeps GPU cool' in most reviews , but really creates a hot spot near VRMs and memory- and this is even before overclocking:
http://media.bestofmicro.com/B/8/600452/original/01-Asus-RX-470-Strix-Doom-Loop.png (from Tomshardware Asus RX470 review)