I want to make measurements by observation. By looking at a car I know its velocity. By carrying a bag I know exactly how heavy it is. By hearing a sound I know all the frequencies within.

It isn't super useful for anyone, but I think it would be so cool if numbers just comes up next to an object.

Teleportation is up there, but I think shapeshifting beats it out for me by a little.

Not even considering how to use it to help other people, selfishly. I just want my clothes to always fit perfectly, among other things.

I think I would prefer stopping time over teleportation. I'll probably won't be able to save anyone from a fire (depending on how fire would work in stopped time), or just drop a bomb into the desert, but I feel like if I kept my current life, i.e. not become a well known superhero, these points wouldn't be particularly useful.

The ability to stop time would imho be more useful to me. I could take a multi-hour break just in the middle of work and nobody would know. I could have my five more minutes in the morning without feeling guilty or just have a long vacation without using my vacation days.

It may be underrated but I think having magnetos powers could be incredibly useful.

You nailed my top two. Teleportation would make travel super easy and would be the only thing that could get me back to an office for work - got to keep my day job so people don't get suspicious of my powers right? Stopping time is also cool (for extra sleep I swear!) but with the obvious caveat that it's not "all molecules freeze and you can't breathe and you die" style time stoppage but the more sci-fi "you can still move around and do stuff, time just doesn't pass" kind.