TRX is a ton better then nothing. As is say one of those very adjustable cable weight machines and a bench. (You know the kind they often use for rehab)..
I happen to think free weights are the overall best but most gyms are going to have access to all three - especially if they have a dumbell set up..
But these arguments in general are a waste - its like arguing what kind of amplifier is the best. Plenty of amplifiers can do the job extremely well - its going to depending on the speakers source etc.
Guys can get in fabulous shape using all kind of methods..resistance training in general works. Even straight up hammer strength machines can give people real world results..