Depends where you are doing it.
If you are up on the open hill all the time 270. Ranges will be a bit longer probably and it will be a bit easier to shoot
If you are in the woods all the time 308. You can get a big heavy bullet in it at shorter ranges and some would say that will help drop them. Also you will not be smashing a very fast bullet into a deer at close ranges. Needs a bit more shooting on the hill but really its only holding a bit higher than you would with a 270.
Otherwise either will be fine.
If you are up on the open hill all the time 270. Ranges will be a bit longer probably and it will be a bit easier to shoot
If you are in the woods all the time 308. You can get a big heavy bullet in it at shorter ranges and some would say that will help drop them. Also you will not be smashing a very fast bullet into a deer at close ranges. Needs a bit more shooting on the hill but really its only holding a bit higher than you would with a 270.
Otherwise either will be fine.