I had 4 of those listed, Axe Rossi, OS, RB and Sirio. Those not mentioned, sts and ninja. Right now I love the sirio power. Ive got 3, one has 2 gallons, another has one and I just broke the third one in. I cant say its going to out last the OS v spec, it made 10 gallons and is now a paper weight, but so far, sirio hands down.
The RB C5bb I had never did run right, come to find out the lower case has a crack in it (now a paper weight). The sts engine, it was cheap so I though I would try it out, never again (gave it awat). The ninja was great, smoooth power and never flamed (sold with hot bodies truggy). The axe rossi was a mamba (hot mod) it flat out screamed, busted a con rod after 6 gallons and it too is a papper weight.
Its hard to say this one is better than that one. Right now my sirios have me sold.