I have an A4A account... I had Manhunt, but it was basically worthless.
I find that A4A, Grindr, Manhunt etc etc are only as good as the local pool you're drawing from. My pool is altogether small. If I open A4A I recognize almost everyone on the list for my town... just from being out and social. If you've been out to the gay bar a few times, you've seen all the wares that A4A has to offer.
Scruff is another matter... the global feature is actually kinda fun because I see friends on there that I know from Ohio and Oregon and California and I can use it as a much more "strictly social" messenger.
That said, A4A... I met both my ex boyfriends on there so I can't really knock it too hard.