The Supertramp is the best, TP next then the rest. 'I' think the difference is in the quality of the cushion that covers the springs. Frames and beds seem the same.
With 3 boys I would defo go for the 14ft. If you come up you can try out a 14ft and a 12ft (next doors!)
OMG Anteater - the Supertramp are rather expensive!! At the same time, I don't mind paying if I really do get better quality and it's safer for the kids. With 3 little boys who should use it for a really good number of years yet, I don't want to scrimp if we'll lose out eventually.