Ion cannons, pd ions, and fusion cannons.
Fusion cannons don't really do anything special to warrant their use. Especially if you have unlocked force lances.
ion cannons are just kinda there too, heavy ions got a warp effect (which I am not sure if the effect is in game yet) but there is little to switch to them from turbos.
Pd ions there is no reason to switch to these, if you stick with lasers you get two upgrades, one to increase the amount of shots, and one to pierce armor, making them freaking useful, and that effect carries over to turbo pd. And pd coil guns have shield piercing and eventually a mod for long range, making them a good choice as well. Pd ions need something to make them an attractive choice, something inherent to ion cannons.