As seen in the JLA arc, he's got a 4-D imp backing him up....
So he kinda wins.
I'd say he wins, generally. He can pretty much control any sort of energy, and has a lot more durability and strength than Magneto.
The only reason Magneto might take it is his vast experience. Triumph has spent a lot of his life without powers, and doesn't seem to use them very creatively (in his, admittedly, very few appearances), so Magneto might beat him out of sheer cleverness.
Qwsp. He was basically Aquaman's version of Mxzy, and when Aquaman got dark (beard, hook-hand), he thought it would be fun to become "grim and gritty," too.
And yeah, Truimph only got his power restored by him, and didn't actually have any 4-D powers or aid himself.
Gender: Male Location: Drinking gasoline. Pissing napalm.
Ahem. It was a 5-D Genie. Lkz or something like that. And all that thing did to help him was give him back his powers, because prior to that Triumph had been depowered. Triumph can control the electromagnetic spectrum and amp his stats...Like Magneto.
Magneto has more experience, but I'd say Triumph takes a 6/10 majority anyway.