I always use the chrome 12pts for confined spaces and 12 pt head bolts and always bought the 6 point impact sockets. I never found a need for 6 point chromes, b/c if you are really beating on a bolt that hard the impact socket seems to do the job better. There are a lot of applications out there that require a 12pt socket used like dxdexter said earlier.
Craftsman and Snapon have the same warranty, so I would go with what your financial standing and your gut feeling is on selling or keeping the sockets.
I have some 12pt Craftsmans that I've use professionally for 8 years with breaker bars, reducers from 3/4 impact to 1/2 socket and have not broken or enlarged the end of the socket yet. The chrome 6 points on the other hand I have had 6 sockets split along the corner of the 6pt. I used a 1/2 12pt metric socket that I beat onto a inner bud lug nut to remove it and realized I did not bring the adaptor with me to go from 1/2 to 3/4, so I tried to remove it, would not come off, the tire man and I cut the socket in half except for the front 1/8" on both sides of the socket and then starting hitting it with a truck bead hammer, it took a half hour or so to break the socket in half.
I have seen plenty of Snapon, Mac, Matco and plenty of other brands break, as long as it has a good warranty and it's in your price range, don't worry what others think about your tools.