Where I am we have Global House, south in Pranburi, Thai Watsudu, north heading towards Cha am and Home Pro, central, in Market Village Mall, above Tesco's. I suspect the latter only does well because of it's location.
I think IKEA would be generally too expensive for Korat. I use the one at MegaBangNa, which is the original, and two stores in Bkk still feeds a huge market of potential buyers, which I don't think Korat has.