Here i go breaking my lurking vow, but this thread is pretty nice considering what fan discussions about which FF is the best usually turn out to be in other places~
My all time favorite FF, RPG and game is FFVIII. As others said, the main fault of its battle system is being too exploitable, and the Aura > Meltdown > Renzokuken combo allowing you to plow through every possible endgame challenge with ease.
I heard lots of people complaining "you have to spend an hour drawing 100 of every spell at the start", while that was obviously not necessary and plain exploiting of the drawing system. There are just too many ways to gain an unfair advantage in the game, ultimately spoiling the whole experience.
My favorite features of VIII are the scenario (the world), Nomura's excellent designs (The Ragnarok... i still dream about it at night) and my idol's, Kazushige Nojima's writing. (It admittedly loses focus near the end of the game, though)
Considering the opinions i heard across the years, the FF8 gaming trend often goes this way for people who actually don't get to hate the story and characters instantly:
first playthrough: don't understand junction and GF leveling immediately > underpowered near the end > fail to finish
late playthrough: through gaming + guides > overpowered > lose interest near the end
Between the two examples one usually sees the ending once or twice.
Had i the time and resources to rework VIII like people are seemingly starting to do with VII, i would definitely:
- nerf or remove Meltdown
- remove the "hidden" drawing points on the two lv100 islands
- slightly increase the enemy levels (or simply increase level variance across common enemies)
- give all enemies a limited amount of spells that can be drawn in one fight and limit drawing effectiveness to SeeD Rank
- add a few drawing points to the world
- make more stats open for junction in the start (more "J [skill]" abilities)
- make the GF learning trees all visible from the start (or make an in-game tutorial about them...)
- increase APs necessary to learn Tier 2 and especially Tier 3 spell crafting skills
- slightly decrease the output of spell crafting
This way you will have fewer spells of the same kind and weaker junctions at the start (no more having more HP than bosses), being still able to craft your spells from items thanks to GF skills as you go on.
At the very least i think the duel at the end of the first disk should be actually difficult for the player...
In conclusion, i believe the ideas behind FF8's battle system were as good as the ones behind FF7 (if not better), but the balancing and the easy exploits ruined them. With the proposed fixes the various spell crafting skills would become more useful in the course of the game and the increased difficulty would make combat more enjoyable.
After all, remember how many times you used tier 2 spells in VIII. Probably not many as you could easily craft 100 tier 3 spells from items by the time they started to appear on monsters.