I Myself have both a KSC Glock 17 and have used the TM Glock 17 as well. There are Pro and Cons of one and the other, KSC is great but the consistency of the gas distribution is terrible when you shoot, TM however is great and is consistent with each shot.
However the TM mags have lots of issues and they tend to be more prone to leaking than KSC mags, I've had my KSC 17 Mags for 3 years now and have been abusing them a lot. for example dropping them into mud, sand, rocks, concrete, and whatnot and yet they still run fine for some reason :O, TM mags however have lots of leaking problems if you do not baby them. the O ring tends to shrivel up faster than KSC mags and causes it to leak gas, over all if you want to spend lots of money on mags, then TM is the best, if you are fine with inconsistency but durable magazines then well use KSC
THIS IS ALL FROM PERSONAL EXPERIENCE don't judge
