I'd REALLY love a forearm half sleeve.
But they aren't really futureproof, and you never know whats gonna happen in the future.
So I've settled on having a leg tattoo.
I think they look really nice. (though not always on super duper hairy legs)
If you're young, you can always save your arms until later. I'm sure you'll still have arms then
You'd be surprised how much short sleeve shirts fail to cover.
Its ultimately up to you though