My second choice for a motorcycle oil would depend on which motorcycle. I am very familiar and tried several oils for my K1200LT. I decided AMSOIL was my best choice. I'd probably pick the BMW synthetic as my second choice since I've read about some high mileage success stories using double the BMW recommended oil change interval, the price is fair and readily available. A big deal for me as I don't want to change oil and filter every 6,000 miles when I ride up to 36,000 miles a year. And I want a warranty. A lot of BMW K1200LT riders on the forum I participate in use these two oils and they have good reputations and results.
For another bike, I'd spend alot of time on forums that pertain to that motorcycle so I could get some insight as to what people are doing and the oils they like. I'd also refer to the AMSOIL Motorcycle report and probably eliminate the bottom half right off the bat. For the above mentioned Suzuki, I'd consider the Synthetic Suzuki oil that just came out. I've heard from one rider that it performed as well as AMSOIL in his Suzuki cruiser. I've tried to find the data sheet for this oil, but haven't found one yet. If I could, I'd compare the properties to other oils I'd consider. Once I narrowed my decision down to two oils, I'd try them both.
For me, the JASO MA was not an issue. I have a dry clutch on my bike. For others that have a wet clutch, I consider JASO MA a must. In the past I've had to replace wet clutches when I used Shell Rotella and Mobil 1, when if I had used a motorcycle specific oil with JASO MA, I might not have. I had just started using AMSOIL car oil in my ST1100 right before the JASO MA standard came out in 1998, and decided I better switch to a motorcycle specific JASO MA oil, so went to Mobil1 motorcycle oil.
Even though AMSOIL may not certify through JASO, I feel very comfortable knowing they have formulated and done the JASO MA testing for their motorcycle specific oils. I have heard that in a few Yamaha dirt bikes and cruisers with weakly designed and worn clutches, that the Yamalube oil seems to make the wet clutches slip less than AMSOIL. But I also regularly ride with many other Yamaha riders that notice a big improvement in shifting, lower temps, less vibration, better performance with AMSOIL over Yamalube.