Which level 7 creature is the best, and why?

2 hobo, the calculations are certainly good. BUT!!! Either you run the battle on auto-battle (and then the archer moves first and attacks the monster, consequently losing), or you do it manually (and then the monster defends on the second turn and also kills the archer). That's exactly why it's considered that archers lose, and you don't even need to take the maximum damage...

P.S. And thanks a lot for the complete answer and numerical justifications...