These shows are in a way comparable to Star Wars.
Farscape is the OT. Original, unique, groundbreaking, magical, unlike anything you've seen before and totally captivating.
Babylon 5 is the PT. Talky, wooden, dull, overly concerned with story instead of storytelling, but still has moments of sheer brilliance (mostly during seasons 3 and 4).
It is indeed like comparing apples and oranges. You can't really compare the two shows. But if you haven't seen either one, I'd recommend you start with Farscape.