I prefer the look of glass tanks. I like to have the tank where I can see it and see what's up, the plastic tubs - while I totally appreciate how useful they are and why they are so preferred - are just not my thing. Glass is a bit harder to keep the numbers right but it's not so bad, once they're set you don't have to fiddle with it much. I think that while glass looks nicer, tubs are a touch easier to manage and personalize.