Hmm.Marko / Marco actually reminds me more of marker than Markel does, b/c of the emphasis on the 1st syllable. I quite like Markel, actually! I could probably use Marquette, too, but that's really similar to market! ;oP
Then use Markel! :) It all depends on what YOU want. Honestly, I'd rather you use Markel than Marquette, and Markeldoes go with the first name, so it's not like it doesn't flow or anything.