I love onion rings and these were almost gross. I used whole wheat flour and bread crumbs and the rings tasted like powdered cardboard. They did get very crunchy.
I think the main reason mine were not very good is the lack of fat. I didn't have cooking spray which meant that the coating was very dry and didn't brown properly. When I realized this was happening, I tried to fix it by lightly drizzling olive oil over them. Obviously, pouring oil on rings sort of blew the idea that they were healthy and since I couldn't evenly distribute the oil, it only made them moderately better.
I think I will try this again, and toy with 3 things: omitting the flouring step (since the flour seemed to be a prominent flavor in the result); Try stronger flavorings (I just did salt and a grated parmesan/romano blend in the crumbs); Have olive oil cooking spray and use it thoroughly. I will definitely use something different for bread crumbs, but probably still use whole wheat.