I'd agree with you about the 4-2-3-1 at the moment. It's a brilliantly well-rounded formation suited to current European and international football. Mourinho's Real use it at present and it seems to be working fairly well.
4-3-3 is by far a more inherently 'beautiful' formation to watch, due to its attacking nature. Barca have got the style down to and absolute T. They are the best team. Ever. So to judge 4-3-3 on Barca would be unwise.
A personal favourite of mine, however, is the 3-4-2-1. I've never seen it deployed as an attacking formation effectively, as it more often than not turns into a 5-2-2-1 with the RM/LMs turning into wing-backs. I believe, with a technically excellent, attacking side it could be deadly though. Basically a 3-4-3 but the wingers tuck inside, allowing the wide midfielders to run the flanks.