I was always all about larger sized tanks (I say larger I mean 40g and up) but lately I've been setting up some 20 longs and a bunch of 10g and I'm beginning to think I like them better. They're easier to light and filter, and you can fill them out a lot easier and cheaper than a larger tank with plants. I also just like the fact that they're sort of small microcosms. I'm scaling down my tanks to just one 55g and one 46g, the rest are 20g and under. I guess for some people bigger always isn't better.