This quick numerical analysis suggests the following categories.
Comprehend Languages -- Suggest making underpowered
Read Magic -- Suggest making underpowered
Tenser's Floating Disk
HIGH POWERED LEVEL I SPELLS
LOWER POWERED LEVEL I SPELLS
Affect Normal Fires
Mount -- Suggest making standard powered
Nystul's Magic Aura
My first problem is that there are too many spells. There's a lot of crap there I think and its hard to remember.
In any event, I think the top three picks are good candidates for over poweredness. Magic Missile is a staple for mid and higher level characters, who often fill their slots with nothing but magic missile to be gatling guns. Sleep is a nuke. Charm Person is often spammed. I'd slap a material component on them.
There are a lot of underpowered spells. I would move read magic and comprehend languages down to underpowered to pair them up with their weak reversals (or vice versa). I would move Mount up to the standard power because I find it to be very versatile and handy. I think you'd be safe making all those Underpowered spells level 0 cantrips, however.