There's no such thing as best, only best for you. It's up to you to research your choices and decide which one you think will suit your purposes.
I'd never heard of btrfs before, but a quick dash to Wikipedia tells me that it's designed more for enterprise use, particularly for the anticipated future need to handle very large amounts of storage.
ext4, on the other hand, is simply an extension/improvement of the current ext* series, and backwards compatible with these. It patches up some problems in the old systems and adds a few incremental benefits, so it should be good enough (at least) for most home/workstation purposes.
Unless you have a special need to use something exotic, I've found that it's generally better to stick with the standard offerings. In my experience, the effort it takes to maintain non-standard systems usually outweighs the benefits they provide.