For Final Fantasy, I would pick any Final Fantasy numbered 6 through 10. They had the highest production values for their time and aren't frustrating. They revolutionized the JRPG genre as we know it and set the expectations of the genre in terms of characters, plot structure, presentation, music, etc. You collect a band of quirky heroes and go on a journey to fight evil empires or megacoroporations, and then fight some god monster at the end. They are each 20 to 40 hours long. Pick whichever one appeals to you the most.
I have to disagree, FF7 can be really frustrating. First of all, there are the usual frequent random encounters. I haven't got any problem old cRPGs like Realms of Arkania or Might and Magic I, but as a western RPG guy, it was a painful aspect. The inventory management can be horrendous, too, especially in the late game with all the materias of the world. And I hate always-laughing so "evil" characters.
I see zero significant issues with random encounters when attached to fun combat & RPG systems. It's kind of the point. The same people that complain about random encounters are probably the same ones that complain about respawning enemies of any kind, period. Good games most commonly have combat, and a lot of it. Random encounters in particular punish bad navigational skills of the player, chipping away at resources (various healing items, mana stock, etc) and great games take advantage of this fact, even in FF games at times, especially particular dungeons with maze-like design.
I assume those with no appreciation for respawning enemies or rand encounters generally don't have much appreciation for gameplay, more in it for the audio/visual/story/whatever else side of things. Yeah you could say FF7 in particular the random encounters may get annoying because the combat is too easy and therefore lacks true substance, but that doesn't explain hatred for random encounters in games with more testing combat. Also I will never stop recommending this:
FF7 Hardtype Romhack