Best autolocking mechanism?

I was considering getting an autolocking carabiner (mainly for belaying) but even if I did decide I wanted an autolocker there are so many to choose from. My top 2 choices are one of the grivel twin gates (which one would be best for belaying?) and the black diamond magnetron rocklock. I like the grivel because of how grit/grime/cold proof it looks and I like the magnetron because of how easy it seems. If you had to choose an autolocker for belaying would you go for a twin gate or a magnetron?

Of the two you listed - Magnetron.  Simple system and easier to clip into a belay device.

Honestly, I think you're over thinking it a bit.  Unless you're REALLY using that biner in nasty, gritty situations, grime isn't a concern 99% of the time and if it is, you just wash the biner.  

Give a hard look at the Edelrid Slider mechanism.  Now my favorite lockers as they're super low profile.

For belaying I would personally go with a magnetron.  I am also a fan of the Edelrid slider.  The twingate has the one major distinction of being the only autolocker on the market (that I am aware of) which allows you to clip a rope into it one handed.  But having to manipulate that outer gate makes it a bit clunky.  Heres a rundown.

Twingate:
+ Rope can be clipped into it one handed
- I find it a bit cumbersome to use with a belay device.  You have to thread the outer gate through/over whatever you clip it to.  In the case of a belay device, this means you either have to pull a bigger loop through the device before you can clip it, or you have to rotate biner
- Maybe not quite as secure of a locking mechanism.
- The solid gate models have a pretty small gate opening.  The newer wire gate models may be better.
- Hooked noses.

Magnetron:
+ Smooth Keyed nose.
+ Super secure locking mechanism
+ light weight
- Takes two hands to clip a rope into it.  
- Maybe it is prone to getting jammed with grime (I haven't had this problem) or iced up.

Edelrid Slider:
* All the benefits of the Magnetron, but even easier to operate at the cost of possibly being less secure (meh).

Pirate WireEye Autolock Carabiner :) Really awesome autolocking biner

Edelrid slider, great idea, but once they start sticking open it's a different story. I tried cleaning/lubing them to keep them working, but all eventually succumbed to sticking. Luckily edelrid replaced all of mine with screwgates.

My favorite also used to be the Rock Exotica Pirate wire eye, but after wearing through several I changed to edelrid HMS Bulletproof Triple FG. The gate action is different from the Pirate, but once used to it, has the same functionality, and stainless steel wear surface.

I really like the Mad Rock Ultra Tech Twist Lock.  Now, it would be too small a diameter for belaying with anythign other than a GriGri, but I use them for anchors and they are very smooth.

The Petzl Am’D with the Triact-lock is by far my favorite minimum hassle auto locker. Magnetron’s in my experience become weak at the gate and have too much play after a lot of use. My Am’Ds are strong as ever after 4 years. Ultra solid locking mechanism.

ChadMartino wrote: The Petzl Am’D with the Triact-lock is by far my favorite minimum hassle auto locker. Magnetron’s in my experience become weak at the gate and have too much play after a lot of use. My Am’Ds are strong as ever after 4 years. Ultra solid locking mechanism.

Play in what aspect?

My favorite is the DMM Locksafe mechanism.

David Fox wrote:

Play in what aspect?

Wobbly gate broh 

Skeet

Edelrid sliders are sticking after <1 yr of use, Magnetron is sticking after <6 months(and wobbly gate broh).  Cleaning them doesn't seem to help. Neat ideas but that's about it.
Plus even after "getting used to" the Magnetron it is still just annoying to use. 

If you are using a tuber I would get an HMS style biner.

If you are using a gri-gri then the Am'D with the red gate cannot be beat for ease of use and superior handling.

Do not buy an "anti-cross loading" locker its a bunch of bullshit.

I like the Black Diamond twist locks. This is really a question of personal preference.

I also use a Clepsydra small for a grigri and love it. It does have a clean nose, unlike some of their earlier twin gates. I believe that the larger Clepsydra does as well, but don't recall for sure.For a grigri the motion putting it on is incredibly fast and intuitive. I haven't used a twin gate with a tube style device. 

I used an edelrid strike HMS for a bit, I also had issues with small debris in the locking mechanism. Much more annoying though was that you had to manually pull the anti cross loading wire outward to slide into a belay loop, I found it cumbersome.

I've used the magnetrons and personally hate the way that they open. Gridlocks are a stupid PITA for a grigri and poor choice there, fine for tube devices. 

You are over thinking this. In a year you'll have a dozen different biners.

For atc style, pilot I like the DMM rhino.  For grigri I like the DMM sentinel.  I have a couple with the tri-action lock safe, but mostly I use screw locks.

go twin gate. I use a lambda k7g. also check out the grivel tau.

Magnetron is definitely a one handed carabiner once you spend a couple minutes playing with it (spine against web between the thumb and finger, use the same thumb and finger to unlock). I have noticed it is much easier with the bigger version. It can freeze, but usually only happens if you get snow on it which is rare for a belay biner. Easily (relatively) solved with a tap of an ice axe, which I think is an underrated quality. Try unscrewing a frozen screw gate without pliers...

That said, just pick one (one being the key word). Screw gates are tough to beat.

I've been using the magnetrons for a few years and love them.  If you're in an area with a lot of ferrous (iron) rock or planning to ice climbthen they can be less useful. I have 2 of the larger and 2 of the smaller and will probably get one more of each sometime soon. I take a lot of new people out so I put them on TR anchors where they can't unscrew each other like screwgates and I hate not having them for my belay device when I do that. 

Andy W wrote: go twin gate. I use a lambda k7g. also check out the grivel tau.

I have always been curious about these. They seem like a hassle to clip, but I have only handled them in the store.