Are you asking which is the best engine? or which complete package is best?
I would say the MNR with a new ZX10 engine would be best. Not the most powerfull but the best deal and not slow.
Engine wise its the busa, but its a lot of money and thats why i went ZX12 when i upgraded from an old CBR1000F engine. A massive difference and so much nicer to drive and run.
Mk Indy and Mac 1 are the next ones.
However i think the Dax rush is the best looking, just heavy and large so better suited to V8's (which i love too). The dax is like a hotrod version of the others mentioned above IMHO.
If i was going to build one myself now i would go single seater and R1, i bet they get even more attention than the one i already have.