I'm not quite sure but it's definitely a good question.
But I'll go throgh all possibilities:
Francis: Though the advantage that he moved away from home and has now his on life so he won't make your life a living hell (like my older sister who lives in the same small town like me and distracts my life all the time^^) I would say: NO...but nevertheless he's cool.
Jamie: ah, ah..no...too young, too loud, too creepy, too stinky, too annoying ^^
Reese: before I say something wrong...NO
but he's cool
Malcolm: well...I wish I could say it was him, that's why this question is so tough but I think we share a lot of similar characteristics (which would be the perfect "match"
) but I guess that would be the problem. We are both kinda pigheaded loners which would cause only trouble but hey...try before buy...I wouldn't say no but it's not a clear yes.
Dewey: he seems or seemed to be a kind of annoying creep but that's not entirely his own fault ya know...his brothers gave him enough reasons to be like this. With me as brother he would learn a lot of things (although I'm often tending to be this "loner" I care for other people) and I guess he would be a total different person. Basically he's nice, someone you can get along, annoying just were it is necessary (I can understand that^^) He reminds me of myself, throwing yourself to the ground if you don't get what you want, screaming and crying..that's me years ago.
( I think I stopped this behaviour at 12 lol) Though I like Malcolm as character I would adopt Dewey as brother.
I'm referring to the characters of the show, not the real life personas. That would be a quite different question.