Playing either is decently easy, but mastering them is hard.

If you have a sense of rhytmn and can keep a beat, the drums would be probably be better, but once again, mastering it would be harder.

If you have fast fingers and can multi-task a decent amount, then go for guitar.

Neither is really "easy" to learn quickly though.

drum more easier to learn than guitar, because not needed to learn melody, chord etc. just rhytm, speed etc.
but more complicated when you practices that, if guitar you can playing it everywhere.