Crickets
Crickets are widely available and trigger feeding responses well, but they can hide in décor or burrow into loose substrate. Remove uneaten crickets before a moult.
Locusts
Locusts are active, easy to see and usually stay above ground, which can make uneaten prey easier to recover. Size them carefully for smaller spiders.
Nutrition
Use healthy feeder insects and vary prey where convenient. The tarantula does not need a complicated menu, but feeders themselves should not be starved or in poor condition.
Choose by the enclosure
In a deep fossorial enclosure, prey that disappears underground is harder to monitor. In a simple terrestrial setup, either feeder can be easy to manage.