Swiftkey is what I found to work the best. It puts symbols on keys (e.g. long press m to make /), can make symbols like × by long-pressing *, can have a number row above the keyboard, and the predictions are some of the best as far as I've been able to tell.
I also don't mistrust Microsoft that much, since they don't have a data-oriented profit model, so even if the firewall is slow to boot up and lets it upload a backlog, even then it should be okayish.
I made the mistake of updating it once, though, and got an uglier design and now need to press two buttons to get into incognito mode rather than just one. Lesson learned: never change a nice system if it's fully firewalled and isolated... or at least have a planned retreat.
I also don't mistrust Microsoft that much, since they don't have a data-oriented profit model, so even if the firewall is slow to boot up and lets it upload a backlog, even then it should be okayish.
I made the mistake of updating it once, though, and got an uglier design and now need to press two buttons to get into incognito mode rather than just one. Lesson learned: never change a nice system if it's fully firewalled and isolated... or at least have a planned retreat.