Shell VSX (full synthetic) (as I could get it for a really great price)
I ran that in my:
TRX850 for 5 years/85,000Km's.
XR250 for 4 years and lotsa K's (was changed after every weekend of riding maybe 10,000K')
4 years in my 900 Hornet and 24,000 kms
In my 2 stroke race bike I ran Shell gearbox oil, and premix oil (except for the time I got some ELF oil for $17 a litre)
I run Shell helix in my Diesel ute.
I have a mate that ran Motul 5100 full synthetic on his superduke and had some serious scoring on one of the cams and had to get a top end rebuild and reground cams within 12 months of buying the thing 2nd hand. (Not happy as KTM were not too supportive and he had to pay for it himself as was weeks outside of warranty)
I reckon its hard to get a bad oil. some may make changes smoother, but this is trial and error. My advice is to get on one brand and change it often. There is not a lot of oil in bikes that rev a bit more than a car. I also work on the principle that the price of a filter and oil every 6000k's/3000ks respectively is much cheaper than a rebuild.
Now that I have to pay retail prices for oil again*, I may consider other oils, but it would want to be a special price to tempt me from Shell.
*I do not and never have worked for Shell.