If I go back, there is still going forward. If I go forward, there is no going back. So I choose to be able to go back in time.
Also you just die quicker if you travel forward.
Or, I mean... it depends if the timetravelling changes your age as well...
Would you rather be able to make people confess their thoughts and feelings, or to have a foresight ability that allows you to read a persons future like a movie?
(totally didn't get these from My Hero Academia)