Phone you had before your first iPhone.
I had a Motorola Rival beforehand. The phone was properly named since I think the phone’s one purpose in life was to try to annoy me. I went through 3 or 4 warranty phones before my warranty period was up and I couldn’t get any more replacements. The first one just stopped responding at all, the second’s screen just went black and stayed black but the phone was still “alive”, the third’s screen became psychedelic with all sorts of odd colors not disappearing, and the final one I was stuck with would send texts before I was done typing them, it would mute me during phone calls, hang me up in the middle of a phone call, so basically for a year I had a paper weight that was sucking $30 a month and I had people around me let me use their working phones. So I never really got a chance to use it’s keyboard.
Long story short: I went through a painful lesson on how you should always read reviews before buying a product.
I am so glad about my iPhone doesn't cause me problems like that monster.