My first one was a Samsung Galaxy S1 that I got in 2013 and it was a great little device that was easy to open up and repair. It had only 512MB of RAM but that was plenty for basic phone needs, web browsing and running some Android apps like AnkiDroid at the time.
Mine was the T-Mobile G1. Slide out keyboard and track ball. I remember being underwhelmed by Android at the time so I switched to the Nokia N900 for a while which comparitively was more mature than android and iOS at the time.