Well, the Bucks are 20-9 against the West, which is a .690 winning percentage. The Warriors are currently the West's top-seed with a .684 winning percentage. That's effectively a tie.
But that undersells the Bucks, since the Warriors' record includes games against the East. If you applied the Bucks' Western winning percentage to the number of games they've played against their conference (.690 x 49 = 34 wins) and their Eastern winning percentage to their number of out of conference games (.776 x 29 = 22 wins) you get 56 wins. That's 2 wins less than their current 58 and 4 wins more than the Warriors' 54. They'd have a 3 game lead on the Warriors (4 more wins and 2 less losses than the Warriors)
So yeah, they'd probably have the #1 seed if they played in the West. They've been great, regardless of their schedule.