What you got wrong is that 1st, Edo Minato is weaker than Alive Minato. 2nd you say SM Minato like it was suppose to mean anything, Senjutsu enhances the body, Edo's are dead so their bodies can't be enhanced. Why do you think Madara didn't want to become the Juubi Jin as an Edo Tensei? Edo's can be Jinchuuriki as Minato is proof of that but they can't enhance their dead bodies unless they use chakra to enhance their physical capabilities like Tsunade's/Sakura's super strength, Raikage's Lightning Armor, or chakra in the feet to increase your speed.
Pa toad told Naruto Senjutsu awakens the body in a number of ways and we see Naruto's durability greatly enhanced as he fell from the mountain onto a bed of spikes and felt nothing. Also why Edo Madara's body is considered special, it was enhanced in the process of being created. All SM did was give Minato more chakra in the form of Senjutsu (his chakra+natural energy) and he had his chakra absorbed before that so he wouldn't have more chakra than he had arriving at the battle field.
Summary: Alive Minato>Edo SM Minato. Alive Minato>Obito who was trained by Madara, have a better S/T jutsu as stated by Minato, have Hashirama's DNA to boost stamina and power up jutsus, and have intel which all puts Minato at a disadvantage. Obito's only hope to beat Minato is to use Kamui, he knows this, anything else gets dodged or reflected back at himself.