I think Obito would take it this time around. Why? He would have 6 Edo jinchuuriki to occupy Minato whereas he could remain intangible. Minato would tire out after say, 2-3 Edo jinchuuriki (it's hard enough to beat 1 jinchuuriki when they're alive and don't have Sharingan and Rinnegan in each eye, so I'm doing Minato a favor). If he's tired by that point, you know he's not winning; Obito low-diff.
Anyways, it's quite obvious that Minato's still smarter than Obito. But how would that matter when Obito has his Edo jinchuuriki to fight for him? The fact is, this fight doesn't NEED to be a S/T one. If it had to be one, then why isn't Tobirama included in this fight? If they had a S/T fight again, I wouldn't be sure who would win. If Minato were still alive, I'm sure he would've perfected his element with the Rasengan, and would have improved on his S/T; Minato high-diff. If Minato were revived with Edo somehow to fight against Obito with his previous abilities, Obito's taking this mid-diff.