Here is my .02....
I think cheap golf cart type traction batteries *can* be the best deal out there. The thing is, you have to treat them VERY nicely. I have been using the same batteries from Sam's club for 8 years now and they still have some life in them.
However, I charge every day, rain or shine. If solar doesn't do it the generator does. I never let them get below 75% state of charge. The old rule of thumb was that you are supposed to be able to go three days without charge. If you want to do that, you need the good batteries, like Surrettes. For me, I hope to get a decade out of my batteries and then buy a set of the same cheap type.