one was a did 412 and i use motul chain lube, no sure what the other 2 were but think they were crappy ones , i usually have a little slack but not tight or loose
DID are good chains but you might want to step it up to one of the higher tensile ones (Sean01 posted up a good pic somewhere with all the DID chain specs in it). Another one id recommend is Tsubaki. RK get good reviews but ive never used one so dont know first hand.
i allways use the "2 finger" rule for chain tentioning.. sit on the bike and between the swingarm / chain slider and the chain should be able to fit 2 fingers between it. never snapped a chain, not even ****** kmc's!