Funkwerk have had another name change to F.U.N.K.E. for some reason. Their kit is good and reliable, I have fitted 10 of their ATR833 COM units recently. The problems they had with the older transponders were a result of their making a unit that met the spec, but unaware that the spec for ground stations didn't match that for aircraft units; they did a good job sorting out the problem.
TRIG likewise are good and reliable so far - I've fitted lots of TT21/22 transponders with no problems. TY91/92 COM units are quite recent, the only problem with them is they are limited to electret mic inputs. Not a problem with powered aircraft, but many gliders have dynamic boom mic.s and they have to be replaced. For an installation with limited panel room (or depth behind) they are ideal. The price of the COM units is higher than the FUNKE units.
Little recent experience with Becker, who seem to have gone out of fashion; in the past they have made high quality kit.