AV TWR = bad; traffic levels don't justify it, guys & gals sitting doing little to nothing most of the time, thus overly restrictive and not cost effective
UNICOM = bad; untrained unqualified person not able to give relevant directed traffic info or weather obs; even FAA does not include them in any risk mitigation hierarchy for airspace and traffic services
CA/GRS = good; trained person a.k.a. flight service in an AFIZ from years past, directed and specific traffic info, MEL requirement for facility, able to give met obs. cloud & vis & approved source QNH able to be used for lower inst app minima.