I was wondering if anyone had some thoughts or opinions on what they believe is the hardest league to win in? I know the engine is young and new players are joining every day and there is no real criteria for the toughest league, but I though some could help me get a feel for others leagues in MFN.

Hmm, good question. I'd say MFN is most likely the toughest as its the league that most people want to be a part of.
But I'm in cust-10 and my div is the toughest in there IMO, Morbid, jsid and now an inactive :(