It depends on how much you win and how fast the games go. I make considerably more in DM's but you have to win a large percentage of the matches to make a lot of points. If you are a new player you might make more with assists in TDM since there are a lot of opportunities to tag and you may get the win bonus more often than in DM. That being said, TDM's are only really possible when the discord channel sets them up due to the low player base.