GL
My, for me that is a very, very tough choice! But I went for BBC2 because they showed a wide range of variations on the same theme, and they never grew old because of new idents and bumpers, plus they still maintained that same '2' identity for promotions. Also, the fact that they lasted for 10 years, twice as long as the balloon, seems to suggest that they were more successful, though to be fair the balloon wasn't given the chance to explore its full potential!
However, I think that people may have grown more tired of the balloon than the '2' if they had gone on for longer (see the TV and Radio Bits page called 'What If') - although there were numerous possibilities for the balloon, I think that one would probably run out of them eventually, unlike the '2', which could revamp and relaunch itself numerous times, especially on such a diverse, alternative channel such as BBC2.
However, I think that people may have grown more tired of the balloon than the '2' if they had gone on for longer (see the TV and Radio Bits page called 'What If') - although there were numerous possibilities for the balloon, I think that one would probably run out of them eventually, unlike the '2', which could revamp and relaunch itself numerous times, especially on such a diverse, alternative channel such as BBC2.