I own an Xperia Mini Pro SK17i, Cosmo Communicator, Unihertz Titan, and an FxTec Pro-1 X.<p>The best phone by far was the Xperia. Palm sized, smaller than an N900. If they made a modern refresh it would be the perfect phone.<p>The Cosmo Communicator was entertaining for a while. It was also heavy, fragile, uncomfortable/flawed to use in any position (not even touch typing worked all that well despite the amazing keyboard due to its criminal omission of <i>feet</i>). It failed after a year when one of its USB ports shorted out, melting. The port is on a daughterboard, so in theory repairable, but no spares available. Even before that, the sheet metal coverings on it (held by microscopic tabs) were falling off regularly. The build quality was so execrable that even though the Astro Slide looks like a mild ergonomic improvement, Planet Computers will not see the inside of my wallet again.<p>The Titan is my daily driver. It's indestructable and lasts days on battery. I don't trust the stock firmware, so I run LineageOS on it. This comes with a slew of annoyances, rendering the physical keyboard possibly more annoying to use than even a software keyboard would be - touching it incautiously causes wild random scrolling (it's touch sensitive), and it's easy to get the keyboard stuck in symbol mode. The square screen breaks some apps. The headphone jack appears not to work. Still I stick with it because indestructibility turns out to be the thing that keeps me using a phone.<p>I just got the FxTec Pro-1 X. It's slick looking and runs LineageOS just fine, no jank. It's also damned fiddly to open, jumps out of your hand with the spring loading when it does open, and feels like it would not survive a drop. Not a great combo. If I switched to it as a daily driver, I'd give it a month tops before it ended up smashed.