TAG and Gama are both reputable companies. I don't know too much about TAG as a company in terms of working for them but I do know someone that works for Gama.
Apparently they've just announced a big expansion and as such are looking to recruit Ops staff. Lots of aircraft joining the fleet over the next few months and there was a big advert in Flight recently.
There are obviously quite a few Operators at Farnborough but if you want a decent company that pays well has good benefits and what seems like some good career prospects coming up then I would say one of those two would be the guys to speak to.
If you want me to find out some more info for you about working conditions ie rosters etc at Gama then let me know and I can happily ask.