Jellybean, when we were researching, we got the impression that the bugaboo ones had quite a few flaws, based on Which? and customer reviews. That's despite being some of the most expensive!
The icandy ones I don't know so much about, but the uppababy seem to be great ones - the cruz, as I mentioned, was one of the top ones on Which? and is also very lightweight. I don't think the Vista's that different. Hope that helps!