Hello fellow TTG users, I really don't know why I'm writing this but maybe if you want to level up fast.
Note: This is my opinion on the hardcore game modes.

Firstly, almost every gun is 1 shot so you get 100 xp for the kill and 100 xp for the "One shot one kill" medal and if you boost in the air and kill them, that's another 100 xp. That's 300 xp in total. Secondly, if you're almost dead and get a kill, that's 100 xp for the survivor medal and if you jumpshot, you get the one shot one kill medal, jumpshot, survivor and the 100 xp for the kill. That's 400 xp. Also, there are chances of this happening but if you kill the enemy with the highest score, that's another 100 xp and that will be 500 xp a game. Lastly, you get a lot of kills in domination because games are longer in that game mode so you are getting 200-400 xp a kill and with the upcoming double xp tomorrow, all of it will be 400-800 xp. There are downsides to hardcore, people in corners all game, stray bullets, getting team killed, accidental team kill then they hunt you down and kill you.

A good team and winning will give you more match bonus, giving you the maximum xp for leveling up. I range about 20k-30k, depending if I am unlocking challenges during the game. Anyways, this is why I think hardcore is the best game type for XP.