Depends on personal preference. Use both and see which one you prefer.
I used to use FF, but now I use Chrome because I've gotten to use so many other Google services (Calendar, Finance, Gmail, Maps and Drive). I also have an Android smartphone, so it's pretty cool that anything I do on one device is mirrored on the other.
Both are browsers. I prefer firefox over chrome, as firefox is fast, light and there are number of apps that you can install and work with. Chrome is browser by Google and I don't like it much. It is quite heavy and crashes a lot.
Actually Firefox is heavier. But like you I prefer that over Chrome.