If you are staying in the Crescent Lake area (BC, YC, Boardwalk, Swolphin), then use the IG. Otherwise, use the main entrance. The only way to get to the IG is thru the resorts (or parking at DHS and walking all the way up), so there is no easy transport option and you aren’t allowed to park there unless you are a guest or have a reservation. The time to walk over won’t be significantly different from the main entrance or IG.