The Brompton is really the only game in town for urban folding bikes. Uniquely, the Brompton locks into a compact and balanced package that can be comfortably carried in one hand. If you opt for a model with a pannier rack (or buy an EazyWheels kit) the folded bike can be pulled around like a wheeled suitcase. There are lots of good folding bikes, but only one good folded bike.
Depends on what you're looking for. I found the wheel size a bit too small.
I think this is a fair comparison and gives the advantage to the Brompton in small folded size, although its weight is not something to be taken lightly (!) http://anatolyivanov.com/prose/en/AI.7.00109/
