The problem is, any team with Doom on it has the highest chance of victory. Hell, you can team Doom up with Batroc and Rhino, and Doom's team still wins. Hell, chances are Doom does all the work. HE probably already many different set plans to take down every villain he's against on here, possibly even his team members too.
Well, Loki may have moer experience, but that won't necessarily mean he's more clever and craftier than Doom. Remember, Doom's proved himself well against most that you would think should be smarter or clever. Loki's magic might be better, but against the ruuner up for Sorcerer Supreme, it's not by much (in my opinion anyways).