I'll agree with the others.
I had the Tamiya kit and was not too impressed with it. I had major issues with the main landing gear housing fitting to the wings.
It does come with a heap of weapons though, so if you want to put in a little effort, it would not doubt come out quite well. It does have raised panel lines though, so if you prefer recessed, may not be for you.
From memory, i think the Tamiya is a 1986 release, so a little old now.
I haven't seen the HobbyBoss kit myself, but i've heard it's meant to be pretty good. i have the HobbyBoss F-111 and it looks unreal in the box. I've also heard their F-14 is awesome too, so, presumably, the A-10 should be of fairly decent quality as well.