FF7 was the first FF I played as a real "gamer". I remember playing FF1 on my brother's NES and I remember renting FF2/4 and spending all weekend playing up to the moon several times, but I never really felt pulled into the story until FF7. I loved it at the time and I spent easily over 100 hours on it. I bought the guide at some point and I'd spend hours reading it.
I actually finished Dragon Warrior 1-4 as a kid on the NES and I think I enjoyed them a lot more than FF1. I loved the grind to buy the best new weapon in each town, killing the new color of slimes or wyverns.
It's blasphemous, but I haven't even played FF3/6. I enjoyed 8, 9, and 10. Skipped 11 and 12. FF13 was okay, but it lost the part I really love - getting lost in huge towns and open areas. I love exploration. I've since gone back and finished 1 and 2/4. I've played good portions of 2jp, 3jp, and 5, but haven't finished them.