Lately I have had a ton of trouble with trying to settle on an army to use as my main army. Currently I forces for Tyranids, Dark Angels, Grey Knights, and Sisters of Battle. I enjoy playing all of these forces, and like the fluff for each. To be honest, there isn't an army that I do not like the fluff for, hehe.
I like having options when it comes down to make a decision on what to play, but having the options has become somewhat paralyzing when trying to decide which I would like to expand upon. It also doesn't help that I have become enchanted with the Necrons as of late, and have been considering on starting them as my main force.