It's not about the weight class per say but about the fighters that are in it. Right now the most exciting divisions are the Light Welterweight and Welterweight divisions. The Light Middleweight division only really has Canelo and Trout. The Middleweight division is not that bad either with Golovkin,Martinez and a few others.
When each division is at its best for me its easily heavyweight. Right now 140 is hot. 168 good as well.
Historically, I've always been a welterweight guy. Year in and year out that division has offered great fighters and huge matchups. From SRL as a child to the more recent crop of Oscar, Floyd, Cotto, Mosley it has pretty much always been a premier division. I'll watch any good fight and 140 is the deepest division right now, and right in my wheelhouse. I prefer more action than heavies typically provide and a bit more pop than most little, little guys.
With me it changes depending on fighters, first is HW at least it used to be, now 140 to 154, i rarely watch under 122!
SMW Like all but have to say that SMW is the favourite. I have followed that division very closely since the SR Leonard vs T Hearns rematch/SMW unification, that got me hooked on that division. 2 of my favourite fighters pitched together in a rematch. Leonard is arguably my favourite boxer and watching him later in his career perform at a much higher weight at SMW was fantastic, fighting Hearns, Lalonde and Duran.