I like both VI and VII for different reasons, never understood the need some people have to shit on one and put the other on a pedestal.
I remember the snobbish attitude to hate VII upon its release. It was such a hipster reaction, because VII was a lot of westerners first proper experience with a JRPG, while those who had played VI on the SNES were compelled to let you know that they liked Final Fantasy before it was cool to do so.
I was in the group of fans who never played the prior entries, and often hung out in IRC chats with a Cloud screen name (which reminds me, my first ever encounter with a furry was someone who used Seto, RedXIII's dad) so I had to endure those reactions regularly.
I blame the marketing for why VI wasn't initially as big as VII. I saw ads for the game back in the day, but they didn't show anything that appealed to me. It was by chance that I stumbled upon Chrono Trigger (my first Jrpg) and that probably got me to give FFVII a try when I first got a PS1.
On the topic of the thread, there is no objective best FF, as each one does different things better than the others. I had a great time with emulating the GBA ports of IV thru VI (and even I), and you can't go wrong with VII and IX. I only came to appreciate X with its remastered port that I played on VITA.
VIII and XII were slightly disappointing for me at the time (tho they are far from bad games, they just dont hit the highs of the better games, tho VIIIs battle themes are some of the best), while XIII and XV killed any enthusiasm I had for the series going forward.
If I had to pick one that gives the best bang for your buck, it would have to be Tactics, of course.