The ones with zerks are more expensive, but are better IF you regularly grease them. if you don't they aren't much better that the non-greasable kind. they should last darn near forever (or close to it) if greased religiously and dirt is cleaned out regularly.
I'll be using the non-greaseable ones cuz thats what the factory used and hell if the factory ones lasted 200K im fine with not changing them again until 400K. Which is unrealistic. we're not talkin diesel here so 200k is plenty. the truck will be rotting in some boneyard at that point and worn out balljoints will be of minimal concern.
From a technical standpoint the non-zerk ones can get debris in them and ruin them from the inside out but in my experiece this doesnt happen unless you have a mud bog on your commute.
Go with the cheaper ones. even better go to autozone they have a lifetime warranty on there 23-25 dollar ones (non-greasable).
Good luck. my .02
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