Without a doubt, Fender has made some of the worst humbuckers for sale on any guitar ever. They have the notable exception of the Seth Lover-designed Wide-Range Humbucker of the the early 70s, but I've not been impressed with any of the Fender standard humbuckers.
Unfortunately, I don't have any experience with GFS pups. I've always been curious, but since the prices are only slightly cheaper than Seymour Duncan, I've passed. Seymour is a much better-known pup manufacturer, and I trust the info on their website to be pretty accurate. I've had a few pups from him that I didn't care for, but I've always felt like the product was good.
Epiphone's stock pups are pretty much basic Gibson designs made to much lower-quality specs. I've seen Epi HBs that sounded great, and I've heard some that were microphonic on the showroom floor. My old Epi Les Paul still has the stock neck pup, because I am pretty happy with the way that it sounds.
As for other recommendations, Lollar or Fralin make great stuff. Gibson sells humbuckers separately, and they are good as well. WCR, Bare Knuckle, Joe Barden, Rio Grande, Kinman, Harmonic Design... There are entirely too many great pickups on the market. If you can really hone in on what you are looking for, there is somebody making the pup to get you there. The hard part is deciding what you are looking for.
...and if you don't like it, you can suck on an egg.