They're all pretty much the same to be fair - after all it's only a bit of tubing round a GRP hull. Simply buy the one you like !
Remember tho that people are moving back to hardboats now, the RIB became successful because it was so cheap in relation to a good quality hardboat like a Boston Whaler, Dell Quay etc - However now the prices are nearly as dear (and in some cases dearer !!!!) - and people are wising up that they can get a decent hardboat which is going to be more practical for less, especially with the launce of some of the new dories in the market (Selva, Seaswirl, Ramarni etc etc).
In other words - haggle hard - lots on the market, 90% overpriced.