I love P-90s, so all of those sound great (compared to humbuckers). But the SD is just head and shoulders above the others with the Gibson being close behind it. To me, the Lollar was the worst, the highs just sound thin and tinny by comparison and the Fralin was only slightly better.
So, yeah, I agree that the SD sounded very balanced and had lots of that mid grit that P-90s are famous for. To my ears it was the clear winner. (But like I say, I love the sound of P-90s and even the worst of those still sounds great to me!)