I am definitely getting the Switch version. For me, being on a cartridge is the most important thing though. Dark Souls is not a new game to me. Instead I want a version of the game that I can keep coming back to for the rest of my life, and disks are much easier to damage than cartridges. The portability of the Switch is nice too though. Basically the Switch has all of the advantages over the PS4.
This sentiment goes for all games really. Any game that I've already enjoyed enough to play again, I want on the Switch. I have currently collected a lot of consoles, and I would kind of like to get rid of some of them. If I can have one console with most (or all) of my favorite games, then that would be ideal. I am already confident that the Switch will be the best selling console yet, so I am prepared mentally to be in collector's mode and do what I can to collect all of my favorite games on the Switch.