Following the herd means that there's a better chance that someone will have already solved any given problem you encounter and released documentation or a drop-in implementation.
I like the idea of Django/Bottle/etc. because I use Python for a lot of my non-web stuff. But RoR has a bigger and more active population. Unless there's something specific to your situation which changes this equation, you'll save yourself time and effort if you go with the more mainstream option.
Following the herd means that there's a better chance that someone will have already solved any given problem you encounter and released documentation or a drop-in implementation.
I like the idea of Django/Bottle/etc. because I use Python for a lot of my non-web stuff. But RoR has a bigger and more active population. Unless there's something specific to your situation which changes this equation, you'll save yourself time and effort if you go with the more mainstream option.