That depends on your riding style. Most people say MT gives better mileage because its cruising speed is 90-110 and r15 v3 cruising speed is 100 -130 . R15 v3 is designed for top end performance ...
All-in-all we’d say the R15 V4 is a much better proposition, that is if you’re willing to stretch your budget. The MT-15 is a pretty good option as well if your commutes are mostly restricted ...