The only thing square got right in later FF's are the summons

[Lion]

Up to FF9 summons were ridiculously LAME. And by lame it was just your standard fire with a fancy animation and maybe a bit more damage. They didn't feel like summons and if Square remade FF7 I hope they would completely overhaul the summon system of 1997.

Even in FFX summons felt like summons. Of course the fact that most of the time you'd be doing more damage by 3 people attack, summons still had their uses and were a great finisher to overkill and were quite usable throughout the game despite the fact that usually it was more convenient to not summon.

I like how square continues to change how summons work because they were not fun at all pre FFX. Long animations, only worth using in boss fights, high mana costs, damage cap limiting their strength lategame (except for lolKOTR), whatever, they just werent appealing to use. For example in FF4 Rydia can cast flare or summon bahamut. Bahamut does 9999 but Rydias flare is far faster while capable of hitting just as much.

Basically what I'm saying is that summons should be interactive but at the same time something you want to use. Which to be honest I did not use in FFX unless forced to. My experience with FFXII is limited since I stopped playing right after getting my first esper. (story/characters/world was lame)

Summons should feel powerful, but interactive.

[Covarr]

I dunno, FF8's summons were pretty differentiated from standard magic. Separate health and charge time and everything.

[DLPB_]

XII summons were also awful.  X's summons were the best, because they added new playable characters with their own abilities and customisations.

[Hellbringer616]

I agree with DLPB, Though I've heard that FFXII JZS made the summons more like they were in X, though i can't read Japanese, So i didn't bother getting it haha. My friend tried using their English patcher and it failed. thankfully he wasted his money on the game, and not i

[LeonhartGR]

FFXIII's summons were not making too much damage to large enemies and you could only use the leader's one and FFXIII-2 has no summons just monster pets like Pokemon.

[nfitc1]

With enough time and patience you can completely obsolete the summons in FFX by going through the sphere grid and using the celestial weapons. Quick Hitting for 15 times between Nemesis's turns is much better than two hits from an Aeon.

FFIX's summons, while needlessly long (I'm looking at you Ark), can provide enough time for characters at 1 HP regen all the way back up to full while inflicting matchless major damage on the opponent in the process. You can't get that out of any other FF. That would have at least made Eden worth summoning.

FFXII's espers were hit-and-miss. Early on they can be helpful in some situations. Forget about them helping in a boss battle, though. Most just blindly charge in and start wailing on enemies indiscriminately. That'd win against maybe 15% of bosses. Other monsters that you encounter later in the game require more complex strategies.

[Tenko Kuugen]

Having played the translazed Zodiac XII, the espers are practically twenty times as useful as in the original XII