The SIG requires more lubrication on the rails. This is very important to protect the aluminum frame during shooting.
If both are maintained, then the difference is in the trigger and recoil management. The Glock's trigger is much lighter and is easier to master. The SIG's double action trigger takes some time to learn. The bore axis is higher on the SIG, but shooters have to learn the recoil characteristics regardless of model.
Both are good guns. If you cannot decide, buy one of each! This is THR!