OK, using the "He's not won anything so he's not good enough to manage United" is a silly argument in my opinion. Personally, I think he's showing himself to be a very good manager, and he's doing a very good job with Spurs, as he did with Southampton.
However, does that mean I'd want him at United, should Jose leave? I'm not sure about that. I've seen a number of managers down the years who looked great at certain clubs, were being talked about as potential United managers only for things to go south for them. I mean, remember when Moyes was here, and there was that Everton fan in here who was constantly harping on about how lucky they were to have Martinez, how amazing he was etc (can't remember his username, wonder if he's still around, hilarious).
At the same time, I look around at the managers in place currently, who would I want to take over from Jose that is potentially an option? I can't think of anyone to be honest. That's not to say that Jose is doing this perfect job.
As for Poch though, I think he's a good manager. I'll be interested to see how he builds from here if he stays with Spurs, they keep their players, and get an infusion of cash from the new stadium revenue. Or, if he takes a "step up" to a club who is a serious contender currently for CL and the like. At the same time, not sure I'd want United to take that chance.