I just wanted to take a quick perspective of magic that perhaps has been ignored (quite a bit by me) and maybe some of you can suggest a few others...
There are a number of underrated spells that arguably underrated and perhaps if one gives proper attention to them, maybe it will improve balance in the next FF4 hack.
The Summons (other than the Mist Dragon) given to Rydia when she comes back are really really underappreciated. Particularly when Rydia learns the level 3 elementals, people think these summons are worthless, but they really aren't. Here's a quick look at these summons, and the spells they compete against.
Competes vs: level 2 elementals, level 3 elementals
Time to being "obsolete": after learning level 3 elementals
These summons are sometimes called the "poor man's level 3 elementals"... but that's because they are using them wrong.
All level 2 elementals have a base magic power of 64... whereas the 3 summons have a base magic power of 80. It does sound MP cost inefficient for single targets which is true... however, it may be worth exposing elemental weakness, when you consider how magic damage is calculated (consider using Ramuh vs Leviathan if you don't have Thundaga). Once you learn the level 3 elementals, you could be overestimating the power of the summons here as well. These summons always multitarget, so they don't suffer from split damage. The level 3 elementals do. The base power of the level 3 elementals is 256. 3 is the magic number for when a summon may be an appealing alternative option for using an elemental.. as level 3 elementals then have a base power of 85 (= 256/3), so it's not that much of a difference.
Another perspective is looking at this spells, compared to say Edge's Ninjutsu spells... but there are arguments to be made on both ends..
Flame's spell power is 80, just the same as Ifrit and cast faster... but then again, that's limited to Edge's mediocre Wisdom growth.
Blitz's spell power is 160, just the same as Titan and is also cast faster... but also suffers the same issue as Flame... mediocre Wisdom growth.
It would have been a good idea if these summons were boosted at least 10% by the Mist Ring (up to 50% shouldn't hurt too much IMO).. in order to keep them competitive with the level 3 elementals.
Competes with: Virus, Quake
Time to being "obsolete": Quake
Quake is eventually the spell replacement for Titan, so it's kinda hard to root for Titan too much then (I don't understand why the FF4A port didn't even attempt to boost Titan with the Mist Ring, since that is the first summon Rydia is linked to). The base magic power is 160, which is basically any of the elemental summon that expose an elemental weakness. Other than the monsters that are immune to this attack (those that are weak against aerial attacks), this spell is relatively damage efficient.. though relatively weaker than Virus for a single target (Virus has a base spell power of 128). The spell Quake (not the monster version) has a spell power of 200, so it was meant to be a replacement.
If Titan was boosted by the Mist Ring by say 66 to 75%, it would be a nice improvement for an overlooked summon... but alas, noone really thought of this...
I also want to give some attention to the Twin spells... even though tons of randomness is involved with them.. they are relatively underrated for what they do.
Flare/Pyro is pretty powerful given that the spell base power is 120... equivalent to Flood (Ninjutsu spell). This is nearly double any level 2 elemental spell Palom can cast (spell base power of 64). The MP consumption is nicely split towards both twins (10 MP each). The only issue that it has is the "random wisdom" pick... which tends to be annoying as the twins in the early part of the game have their non-vital magic stat be only 1/2 as powerful and it is always multitargeted... still, for a basic spell it is pretty damn powerful.
Comet is the closest thing to any of Rydia's summons.. with a base power of 80, and being auto-multitargeted by default (so split damage is a not a factor) it is a pretty good spell.. even before you get Rydia back. The only real negative is its casting infrequency and the MP consumption doesn't quite matchup with Rydia's elemental summons (20 MP for each twin vs 30 MP for the elemental summons). It is still a relatively solid spell though.
Ok.. enough of this for now.. but these are some interesting considerations to look at..