I favor any design that offers adjustable caster and camber. The FF is, unfortunately, pre-set in their design... I'm aware of some cars getting up to almost 5 pos caster and about neg 2 camber.... that is great but.. not guaranteed with all cars.
The SPC design has had past breakage issues... at least reported in some other older posts... I've never actually seen a broken SPC UCA. Regardless, I still like their overall design.. and may someday try them.
Then... there's the Hotchkis UCAs... a good design, but requires relocating one of the attachment points... supposedly, improving bump-steer.
I'd say... you pay for what you get.
Personally, I have modified factory UCAs that give me, at my current settings, 5.5 pos caster, 1.5 neg camber... have run them for past 40 years... works great.
Also,, consider installing the Moog offset UCA bushings,,, installed opposite of their directions... will give you more positive caster and neg camber.
I have Hotchkiss on order for three months now, supposed to ship in Feb. I just want to improve the caster and get rid of the negative camber at full extension of the front suspension ( drag race)
My stock arms/suspension so far is pretty good to me, but maybe im used to it? LOL have been as fast as 160mph