Aww!
Gassymexican
Seananners
Markiplier
TheRPGMinx
Cryatoic
Peanutbuttergammer
Rooster Teeth/Achievement Hunter
JonTron
Jim Sterling
Yahtzee
ScrewAttack
James Rolfe (Angry Video Game Nerd)
The Game Theorists
DidYouKnowGaming
Caddicarus
PeanutButterGamer.
They're the only guys I watch pretty much ALL content from (aka: Favorites). I've grown up with a few of them and have been watching them since they started out (Rooster Teeth, AVGN, Screw Attack) so my opinion on them is pretty biased (considering I've been watching them for around half my life).
Others like Jim Sterling, Yahtzee and JonTron are probably my favorite of 'more recent' gaming videos. They just never fail to make me laugh and in the case of Jim and Yahtzee, they usually have something interesting to say as well as not being afraid to say something others may not agree with.
DYKG and Game Theorists are possibly some of the more 'interesting' gaming youtubers, though I wouldn't say they're funny (even though Mat Pat tries to be)
You're not old??
Chuggaaconroy
MaseaAnela
TheRunawayGuys
Markiplier
JackSepticEye
Cryotic
TamashiiHiroka
TheJWittz
Game Grumps
KittyKatGaming
AttackingTucans
PBG
ProJared
MunchingOrange
there is a guy i just subscribed last night but icr how to spell his username. oh and there is a lot more but i dont feel like listing them all