I also keep wanting to go back to the old stages!
I love prestige too. I'm deep into a cookie clicker run and the ascension is so critical to my feeling ok about my life lol.
I'll think about the full upgrade roster for prestige. In the new design, you have to climb through the stages to unlock each upgrade, but once unlocked, you can access them backward and forward in every stage. My preference would be a full wipe (minus achievements and multipliers) for prestige... but if that's a bad vibe because it's too tedious to unlock the upgrades, I will absolutely keep your feedback in mind!