Depends on the player. But they are quite different. Jugs are easy to learn. Maras are more nuanced but can be very rewarding to play.

Jug tank is amazing in both PvP and PvE, with the best defensive cooldowns in the game. Jug dps is ok in regs PvP but squishy, and poor for solo ranked. however it is viable for PvE.

Mara does great damage in PvP and can be tough to kill if played well. But it has a higher skill floor and only Fury discipline is really viable in ranked PvP. In PvE, both Fury and Annihilation parse well. Carnage is garbage in PvE but it is the easiest spec to learn.

One thing to note: all specs for both Jug and Mara share the same BIS armor set: descent of the fearless. You can swap your gear between toons, making the grind easier. So maybe try both classes and see what you like