The zenith is quite different. It's actually a metalmaker. Each of its meteors obstruct movement and provide reclaim. This means that once you destroy an opponent, it actually adds to the reclaim it creates (mostly for FFA). It's also way more 'fire and forget', the Starlight requires a lot of babying and is mostly good at taking out key structures: The Zenith obliterates bases.
The Zenith should also have more DPS vs, for example, shield grids. I'm not actually sure if this is the case because the Starlights DPS is quite weird.
IMO the Starlight needs a bit of a nerf (It's single target DPS is still insane, more than it needs for 90% of applications, which is mostly killing Superfusions and Mechs), and maybe the others a bit of a buff.
The DRP is definitely not a very interesting or powerful superweapon.
What I really want from super weapons is for each to have a use and a weakness. The Starlights use is single target damage, it's weakness should be in moving the laser from A to B (say from attacking to defense) and in taking out large armies. IMO slow down the traverse rate and lower the DPS a bit.
The Zeniths use is destroying whole bases, messing up terrain and creating metal. It's weakness is vs single high HP enemies, such as mechs.
The DRP I'm not sure, it's sort of a whacky big big bertha.