Stannis a tactical genious? That can't be serious. As far as I'm aware his military ventures to date include being shut up in a castle, having his fleet destroyed, mowing down some wildlings, and letting his army freeze to death.
Rob in terms of military tactician was great, particularly in the books where he gains almost mythical status amoungst the Lannistars as he's so feared. It was his political and emotional side that let him down outside of combat.
He actually reminds me a lot of Edward IV in that sense. A great military mastermind but fucking terrible at politics. Heck Edward IV even married a divorced minor noble woman for love and pissed off all his closest allies after alienating them. Ok parallels with the War of the Roses really are uncanny.