I have always wondered this but never posted it in any forum before. Why do most homebrewers prefer ball lock? Pin Lock has so many advantages over ball lock. You can’t mix up the gas with the beverage post (or vice versa) by accident. Both the gas and beverage QDC come off so much easier and never get stuck (sometimes my Ball Lock kegs have issues going on and off especially when it has sat for a while). And yet, even though I have pin and ball lock kegs I find myself preferring the ball lock for some reason and I can’t figure it out.
Maybe because they are easier to find? But that doesn’t cover your preference at home. They are certainly more sturdy and the QDs are better. Until recently the pin-locks included metal fittings. I use pin-locks for fermenting because they are shorter and fit into my little fridge better. And I can fit more ball-locks into my serving fridge because they are a little thinner. I just found out that there are 2 different sizes of “5 gallon” pin-locks and mine seem to be a little bigger than my ball-locks. Some day I’ll get around to measuring them.
Yeah, I think it is because they are a lot easier to come by. Myself, I use pin, because they just work so much easier in my setup. I had a couple balls, but took them back to the LHBS, and swapped them for pins. So much easier to use, IMO.
I started out with Pin Lock. Here a while back I came across a good deal on a bunch of Ball Lock kegs so I switched basically so I would be compatible with everyone else as there are times I swap kegs with fellow brewers.
I have to say I really prefer the Pin Lock myself as well. We have a Coca Cola plant here so it is actually not hard at all to find Pin Locks here. Coke even still uses them at some accounts around here. I took my daughter to her favorite ice cream shop after school a while back and the Coke driver came in with a dolly full of Pin Locks for the shop/
One of my client radio stations is owned by the local Dr. Pepper Company. All the free cornie kegs I want. They are ball lock . .
That’s why! 
I like pin locks, but I wish they had a pressure relief on the lid like the ball lock units. So much easier than using a spare gas in on the empty kegs all the time.
Pin locks rule!
I ended up getting some pin locks for free, so that’s what I use. The parts aren’t as easy to come by, but they’re still relatively easy to find. No problem with not having a manual pressure relief valve, I just depress the gas poppet with a little screw driver (or whatever is handy) When it comes time to increase my keg collection, I’ll probably buy more pin locks just so I don’t have to buy different disconnects
Huge +1!!!
Some do, some don’t. Most of mine come with relief valve.
Most of mine have a relief valve, just not the keychain type tht you can manually release
All of mine also have a relief valve, just like the couple of 5 gallon ball lock kegs I have. I got the pin lock kegs only because they were on the 3 gallon kegs I bought (easier to lift into a chest freezer). I do prefer the pin locks for security and ease of use, not to mention the smaller size. For me, the only minor inconvenience was in having to have two kinds of fittings.
Gail
I use ball lock because I got on a board full of people adamant that this was the way to go. More people sell them, and therefore parts and connectors for them too. And since I’ve never even seen a pinlock, I don’t know what I’m missing and am happy with what I have.
-OCD
Next time you accidentally put the gas line on in the “Out” post on a beer that has been lagering for 4 weeks and you blow sediment all up into your beer you will know. 
Been there, done that.
I got started on pin locks but switched to ball locks soon thereafter for the reasons stated here earlier…way, way easier to find ball lock kegs compared to pin lock kegs. I own 2 pin locks and 8 ball locks. My two pin locks do not have pressure relief valves. I still use 'em, though.
I got 2 pinlocks from the soda guy here in town. one had a pressure relief and the other did not. he gave me a little cap like tool that locked over the gas in side to relieve the pressure in the one without a relief valve.
It’s a poor carpenter who blames his tools.
As for me, my first keg was ball lock… so, so are all the others. I suspect most people are like that, although with MFL fittings it would be easy enough to use a mix.
all my 5g kegs 17 (?) are pins.
For me, it was an easy choice as the kegerator I have wouldn’t fit Ball locks since they are taller.
That said, I think a lot of brewers like ball lock since they are taller and smaller in diameter - I know if I were using BL, I could fit 8 kegs in my lagering freezer instead of 6. oh well.
BTW, an awl on the gas poppit works just fine for me…
To me the preference was simply a matter of availability. Now it is one of compatibility with the equipment that I have.
Fred
Same here… got a ball lock first, don’t feel like using two different types now.
I also have one ball lock that’s in the form factor of a pin lock. Got it new from NB when I bought the kegging package deal thing a while ago. Made by Cornelius and everything. Wacky…