The Summons in FXV were definitely visually spectacular.
But mechanically I never liked the implementation, from what I remember they basically trigger at random usually when you are low on health. And ultimately they are still just a cool animation.
Also they were really clunky to fight against, both the Titan and Leviathan fights in XV are some of the worst in the game.
Personally I liked their implementation in 7Remake.
It's not as visually striking but I like that the Summons stay around and fight for a while, you can also have them use various abilities and when their time runs out the exit with a cool attack and animation
.
XV so far also seems cool in that you get to physically control at least Ifrit, and the battles against them look awesome.
I do however wonder if there's some sort to use summons in regular battles too, maybe some sort of overdrive attack.