BLM is the epitome of a turret caster with big flashy spells that put out big numbers, which feels amazing when you're able to actually do that. The problem is your DPS plummets the second you have to move at all because of how tight the Enochian timer is and how it works. Having to keep it up for 30+ seconds when the buffs only last 15 and having to switch ice and fire in tandem by casting the right spell at the right time, all while dodging mechanics and making sure you land somewhere within enough time left to actually cast your spell...it's infuriating, for very little actual gain since other classes can do the same or better damage with far less effort and frustration.
I just enjoy SMN because it's a pet class and affords a huge amount of flexibility and survivability in all content. I'll admit the toolkit isn't very Summoner-ish, with the "Summoning" part being mostly relegated to a targettable DoT. I'm not sure how i'd rework it either, but I'd tie the primals and their powers more directly to the class rather tem being more of a side thing. Maybe having them be similar to now, but also having the active one augmenting your spells to do different things. Like Ifrit would make your spells more fire aspected with burn DoT's and fire aesthetics, with Titan being more direct damage and slows or embrittle type things, Garuda would be wind aspected, obviously, with spells for DoT's, slashes, and haste buffs or something.
Another option would be for the Summoner "abilities" being command type spells that affect the egi directly and have almost ALL of the damage come from the pet, so the Summoner is really just a conduit that channels, controls and applies the power of the primals directly to the Egi with supporting abilities that empower and assist the egi. Maybe have the SMN spells be super weak but they cause the egi to attack or do some action, so the Summoner still directly controls everything that's going on and when, but adds a little more of the SMN feel to the class rather it just being the FFXIV equivalent of an Affliction Warlock.