I'm not an expert on lasers, so I'll talk about my opinion on advanced cannon CIWS, mosty about those against missiles, as with the new ammo system I see small, agile missile aircraft becoming the new meta. I've done some testing, and got the best results with 50-100mm 6 barreled cannons firing quick bursts of time fused flak shells.The simultanious explosions of 6 75mm shells take out most medium and almost every small missile, plus there is no wasted ammo, as it changes target after firing one burst.

Quad simple weapons assault gun turrets also got reasonable results against small and medium missiles, for their cost, so if you make such a turret that fits the style of your vehicle you can spam them everywhere.