Bmps are MUCH better. Aren't jpgs like 90% compressed or something?
There's different levels of compression, the more compressed, the smaller the size, but the crappier the result. You can end up with distorted colors and blurred parts. BMPs are huge, but aren't compressed at all, so they have the best possible image quality.
Their size doesn't make them a viable option for posting stuff on the internet however, unless visual fidelity is extremely important.