The benefit of choosing to use an outdoor TV antenna instead of an indoor TV antenna is a reception. An indoor TV antenna has the disadvantages of being smaller and having to receive TV signals through the structure of your home or other building. That typically translates to a less powerful signal and poorer reception. An outdoor TV antenna can be larger and can achieve line of site with the transmitting antenna with no obstructions...
Depending on whether you live in a conurbation or rural area, reception strength should play a role. In rural areas, high reception strength is recommended, as these regions are not as strongly geared to terrestrial TV reception as large cities.