If you want to do some stuff from a quest when player gets to a handfull of locations what would be best to choose?

SM started quest on Change Location Event
or
Start Game Enabled quest with a player alias with a OnLocationChange

I'm looking for performance considerations in the first place if anyone has anything concrete and other considerations are welcome too.

Either will be event driven, so I doubt there would be any difference performance-wise. I'd go with whatever you find easier to work with.