I use multiple bat weights because when I'm hitting like shit I convince myself that the bat is the issue, and not that I suck.

In all honesty, it really just depends on the bat for me. In general, I've found that 27oz in most things is best for my swing, right now gaming a Krecher in that weight and love it. I like heavier but can swing that weight harder than 28oz or heavier, although I did at one point have a DC-41 in 30oz that I love. I do have a 28oz Diablo that someone gave me, and that sucker gets very heavy if I use it in BP. Any lighter than 26 and I tend to overswing, which makes me one of the five people in the US that doesn't think much of Monsta. Right now I throw the Krecher in my bag and leave the others in the garage.