I haven't been in a helicopter but I was in a six seater plane recently - sitting in the co-pilot's seat (don't ask). I found it really great fun even though I'm also afraid of heights. I don't seem to get that fear in planes.

I did recently go up a mountain in Canada in a gondola and that was terrifying! But it was an experience not to be missed.

You should go for the helicopter - I think it will be more like the small plane experience.