I have become a fan of ETS magazines. they work flawlessly and gunmagwarehouse has them for 13.99 can't go wrong there. I also have glock, promag, magpul, and korean mags but I love the clear ETS mags.
Glock, not worth the hassle of bad mags. It's not like they cost hundreds of bucks and magazine issues are one of the most common problems with auto dependability. IME cheap mags may run fine initially but start giving quirky issues down the road. If push came to shove I'd give the Mag pul mags a shot but as it stands now Glock only.
I have an assortment of factory 17s and several Korean 33s. I just got a K 50 rd drum that fits, but needs to load with the bolt held back. Sticks have a small bit of room when fully loaded that isn't available on a drum due to the design. Haven't used it yet. I'll try to get to the range this weekend. If so I'll keep you posted.
I've got OEM 17s, Korean 33s and just got a K 50 rd drum. If you're not familiar with them, you need to lock the bolt back to insert it. Stick mags have a bit of space built in so the mag can be inserted with a closed bolt. Drums do not because of the design. I hope to get to the range this coming weekend, if so, I'll let you know how it works in the subby.
I love the factory Smith & Wesson mags. But I also trust Mecgar. I also have run wit the National 30+ round mags with no problem.
Oh yeah, I have a Pro-Mag that I have loaded to compress the springs, but haven't shot. Thanks for reminding me!