I've had a watermaster for 3 years that I bought on the recomendation of a friend who has used one for quite some time. I hadn't heard of the other rafts but looking briefly at their respective web sites, they appear to be the same. Perhaps they're all made in the same factory and then simply labeled with the different company's name? I know Abel used to sell a raft that also seemed to be identical to the watermaster.
My watermaster is quite lightweight and portable. I'm quite pleased to have purchased a one-man watercraft of this design instead of the more common catamaran-type pontoon raft. The ease and speed of getting the raft ready to fish or to pack it away is a big advantage for me.
My watermaster is the grizzly model. Another friend has the Kodiak model which is slightly larger. I'm glad I bought the smaller raft as it's more than adequate and I don't see benefits of the slightly larger size of the Kodiak outweighing the extra size and weight. Watermaster also shows that they have an ultralight model (15lbs. !) which you might look into. I don't know anything about this model but the obvious question about one would be the durability of the material.