I've been using Swype + Dragon for some years now. I noticed there are 100 times more downloads of Swiftkey so I decided to see what I might be missing.
The answer, as it turns out, is not much. There are differences, but they all are negatives for me. Chief amongst these is the inability to delete a freshly swiped word by pressing backspace without long holding. Seems like a small thing but it really adds up in terms of time + frustration.
Then there is the inability to turn off space following a period. Again, doesn't seem like a big deal, until you swipe a URL which absolutely cannot have spaces of any kind, but has at least a period or two.
Lastly, the usability deal breaker. SwiftKey trails are like fat ugly spray paint marks smeared across the keyboard. Swype offers tidy trails that don't distract or obscure.
I imagine all of these things could be fixed, but what does Swift offer that I don't already get in Swype? Nothing as far as I can tell.
One thing I get with Swype that I'm not getting with Swift is rapid adaptative learning. I absolutely refuse to grant total strangers like Swift access to my texts and emails even for Big Data purposes, even those that somehow might benefit me. I wouldn't allow Swype to do such things either, but then it's never asked me to. I got quality results from Swype almost immediately without them, and of course accuracy has improved over time as I would expect. Unfortunately I can't say the same for Swift, which regularly comes up with howlers as primary suggestions.
While we're on the issue of security. I want an option to create a unique logon. Swype offers that. Swift does not, so I had to provide my Google account. Not happy about that AT ALL. In retrospect, I wish I hadn't. Which means I wished I'd never tried Swift in the first place. Bad news for Swift!
So off Swift goes. I'll keep it in mind for the future, but ONLY if you let me create a unique account first. That's for sure, no matter what Swift manages to offer.