Any marker not milled from a WGP blank body is considered a focker, these include (and I'm sure I'll miss at least 1):
AKA, latest shocktech model, later dye models, SystemX, AIM/advanced concepts bodies, later freeflow models (air challenger), psychoballistics, dragun & odyssey.
Most other bodies with different milling, including eclipse (as far as I remember), were milled from WGP blanks. All of them can have an e-version.
Going into a bit more detail, you could classify them into WGP spec and non-WGP spec, meaning you can either swap everything on a WGP body to them or not.
- Air challenger
- AIM/Advanced concepts**
(*AKA is famous for their merlin spec fockers but they also made WGP spec revenge 'cockers)
(** the only thing you can't swap is the feedneck, it's angel threaded)
Out of the WGP spec clones, air challenger and psychoballistics are infamous for their leaky pneumatics, poor QC and crappy overall tolerances; only worth looking into if you're making a cheap pump, and even then you run the risk of the valve not seating properly (doesn't happen often, but it's not unheard of).
SystemX is pretty decent as far as mechanics go, but the fit and finish on them is kinda rough (I own 1 and have teched a few); that being said, the 3-way is pretty short and the ram on mine is on par with a belsales ram as far as smoothness of stroke goes (it's beyond well broken in though). The LPR is inline with the banjo and is a bigger copy of a bob long alias LPR (I've tuned & polished my marker to hell and back and have run the LPR @ 60 PSI on 15+ BPS as an electro with no shootdown, no o'rings on the bolt help a lot though). The HPR on them is also an improved copy of the bob long torpedo. They are however, forced LP markers, sweetspotting @ about 200 PSI, which turns them into veritable gas hogs, but it's nothing a spring kit can't fix.
Dye and Shocktech are top notch performing and looking markers, though Dye's pneumatics are a bit finicky and some would opt to take them off in favor of something a bit more reliable and then put them back on for wall hanger/sale purposes. There's a reason these brands command a premium even being fockers.
Out of the non-WGP spec bodies (and even WGP spec considered IMO), AKA is king as far as functionality goes, they make the best working focker of all: the "Merlin", it has a huge air chamber balanced with the proper valve and springs, claims have been made of a case off of a 68/4500 tank, but 1600-1800 would probably be a bit more easily attainable for the average joe, this coupled with the inline 3-way and fastest recharging LPR, make for a smooth, fast and efficient marker. That being said, currently, only basic milling is offered and bodies are sold raw so anodizing is (ideally) another consideration to factor into total cost (milling also if you like a flashier looking marker).
AIM/Advanced concepts bodies are on par with WGP as far as mechanics and fit/finish, the only difference is that they're threaded for angel feednecks, so a wider selection is available as far as feednecks. They will otherwise take any other WGP spec part.
Dragun/Odyssey are a mish-mash of 'cocker style function and spyder spec parts, fit/finish were disregarded in favor of low price point. The idea with these is that every kid who couldn't afford a 'cocker could get a similar functioning marker at 1/2-1/3 the price. If you're not into modding (and by modding I mean making parts meant for other markers fit into these), stay away from them, they will only bring you blood, sweat & tears with no reward other than shame and frustration. That being said, 'cocker pneumatics are for the most part compatible and they take merlin spec valves, so a good sleeper can be made with the right parts/knowledge.
That's about as deep into it as I care to go, if I missed any manufacturer (which I'm guessing I did; not sure if CCM/Works, KAPP, FBM, Hybrid & Macdev were made from WGP blanks), they're probably on par with or better than WGP as far as form and function.