I've never finished Super Metroid either, despite owning the game as a kid (I may have just borrowed it from a friend now that I think about it). The game actually used to be quite scary to me, so that's why I didn't play much when I was young. I was probably 14 or 15 when Metroid Prime came out, and to be honest that game scared me a bit as well, but I still managed to beat it multiple times, and I was obsessed with segmented speedruns and sequence breaks for awhile. My username on AIM was FissionMetroid.
There are quite a few in the Metroid series I have yet to finish. Metroid, Super Metroid, Zero Mission, the original Metroid 2. I know that I owned one of the GBA games, and I believe it was Fusion.
For the poll, I voted Prime. The atmosphere was so great in that game and I really enjoyed the exploration. Power-ups hidden in so many places. I remember when my friend told me that you can get up to 255 missiles I couldn't believe it. And with my skill level at the time, fighting the boss of the game without enough energy tanks and missile expansions made it quite tough, such that hunting down these upgrades is very much worthwhile.
