Why do you want to switch? What kinds of problems are you having with your SPDs (knee pain, difficulty in getting in and out?) That would tell us more information and help in making suggestions.

I've used SPDs since the early 90s when I switched from my first-generation LOOKs that I had had since 1986. I don't know when the notion came into existence that SPDs are not for road bikes. Somehow, I missed that memo.