I also only have one!! (except the two nice going out ones)
It's black, only cost me $25 and lasted me almost a year so far. And it's preeetyyy (at least I think so). I always just use ONE, but I must absolutely love it. It takes me ages finding "the one". Then I use it everyday until it's worn out and I get a new black one. I always use black as 1) it's my favourite colour and 2) it goes with all my clothes. I do buy a different style every time I replace the old one. Depending on what I like that time around. It's all I need really. And you don't have to move everything into another bag.

Go the ONE bag!!