Oil is a huge topic! Only ignorant hillbillies think that oil is oil!
Pick a motorcycle specific oil that is API SG/JASO MA and you won't go far wrong. Beyond that, the synthetics have huge advantage over old school petroleum oil, and the ester synthetics have advantages over the other two types of synthetics (yes...there are 3 very different types of synthetics!).
I like Maxima's oils because they have a monster additive package. It is a popular brand, and can be found at many motorcycle shops. They have a low priced petroleum (Premium), a mid priced ester fortified blend (Blend), and an ester based full synthetic (Extra). I recommend Extra for those who want the ultimate in protection.
There are other good brands out there like Motul, Klotz, and Redline. I run Redline, but it is pricey.
In most of the country, 10W40 is a good summer oil, and 5W30 a winter oil. Maybe 20W50 if you are in the very hot south.
Some good reading: