I was buying Quicksilver 20w50 motorcycle oil for a while from Walmart. It started out very cheap and some early analysis indicated it held up well. The price has crept up a couple bucks but still good value.
I've also used the Rotella T6 and I have a couple jugs somehow so I'll probably use it my next couple changes.
Buy, yes, any oil in the specified weight range should be fine, so long as it is suitable for bikes.
As I understand it, look for the "jaso" certification on the back as that is the cert for motorcycle suitability. And make sure it isn't "energy conserving" as those car oils are said to eat clutches (fyi, I know of one fjr owner that claims to have hundreds of thousands of miles on cheap car oil without issue, but I wouldn't do it).
Lastly, ...if you haven't noticed, oil threads tend to elicit a mix of jokes, sarcasm, and criticism. But I get it. You got a new bike and want to know what to put in it!
You are right; Amsoil is said to hold up well, but it is unnecessary in my opinion. Mobil1 synth I have heard holds up nearly as well for about half the price. But the correct answers are all the ones you've been given: any motorcycle oil should be fine.
Welcome! Happy riding.
