Let's take a look at what's guaranteed from a Sky3DS purchase:
- As of right now (FW 9.3.0), you have access to the entire library of 3DS retail games, the eShop, and online play.
- No game limit (previously 10 limit, but new limitless card has been manufactured + tool to remove limit for old cards)
- Plug and Play capabilities (write roms to SD card with their tool, plug SD card into flash card, swap games with one button)
Now let's take a loot at what's not guaranteed from a Sky3DS purchase:
- Any card updates (history shows that the card is not able to be updated, as they put out a new version of the card just to remove the limit)
- Future eShop access (no card updates means the card can get blocked on future firmwares, meaning you will be blocked from eShop unless you update)
- Ability to play future games/online games that get patched
Most of this is known, but it's good to put some objective clarity out there for inexperienced people. If all of that sounds like a good deal for you, then go ahead and make the purchase. Keep in mind that Gateway's (future) solution may guarantee updates and eshop access in the future if they offer emuNAND capabilities, but nothing is known yet. If you don't feel like waiting or have a 9.3.0 3DS somehow, then Sky3DS may be a better choice for you.
Personally I would wait, as I feel Sky3DS' price will drop drastically if Gateway puts forward a solution that offers emuNAND.
Its not if its when, they practically announced it that email a couple of pages back. Emunand support for 9.3 is in the works