If I where you I would go with the Samsung due to a few things.
Samsung is a great product. Also it will last longer and it comes with 5 yr warranty which is overall a wonderful feature..
There's no way to know whether it will last longer or not. Technology moves too fast, and predicting such things based on the last generation is a recipe for disappointment. Just because the 830s lasted well, doesn't mean the 840s will, and especially doesn't mean
your 840 will. Make backups of any important data, and don't purchase a storage device that is too expensive to replace.
There have been scattered reports of bricked 840 drives, FI, with no known reason for it. That doesn't mean you shouldn't buy one, because there are many failure modes, and shit happens. Some drives from every maker get unpredictably bricked. But while it may be worth going with a solid brand, like Samsung or Crucial, as opposed to random SF rebrander with unknown flash quality, so as to hedge your bets, expecting longer service life based just on that, is a step down the slippery slope towards preventable losing important data. Assume at least one of your storage devices will prematurely fail, plan for that eventuality, then be happy when it doesn't happen .
The Samsung 840
Pro, however, does have a better warranty, of the options in the OP.