I'd say you need to look at asic but also how they clock on air, and then hope it scales on cold. I've had four galax ln2 and two did 1900mhz core on ln2, they had asic 66 and 73 and clocked to around 1500 mhz on stock cooler. One did 1800-something with asic 65 and clocked to 1470 on stock. The best did 2000mhz with asic 74 and 1500mhz on stock.
So it's hard to tell...asic can tell you a little bit but i think air oc tells more.
As for asus platinum I got two. One asic 79,x that does 1550 on stock. And one asic 66 that did 1500mhz. Of course i kept the asic 79 Looking forward to test it on ln2!
By the way both had samsung mems.