I prefer the type that uses the single small bearing in the middle. The less points of contact, the less friction.
I have used the modded 39 special case, but was never happy with how they fit the firing pin sleeve very loosely. So I took a small brass rod a little larger than the sleeve, chucked it up in my lathe and turned it to fit the sleeve perfectly. I made the lip the same thickness as the 38 special case. I then uses a center drill and made a tiny pilot hole in the middle just big enough to hold a tiny bearing ball (had a pack of them left over from something).
It works really great and fits like a glove. My BAS had already been shortened for the modded 38 spl case, so I did not have to do anything with it.