I used mars aqua. 0 complaints. It was great, especially for the price, but no features. I believe the vipraspectra has some features i.e timers. I've never used it so I can't speak on much there from experience, but from what I've read they're pretty comparable in terms of strength and quality
I got my new buddy into reefing, and I told him to get the vipraspectra. It has a timer, unlike the mars aqua. He is actually keeping an acropora halfway down 40B alive.
i think the viperspectra has a better spectrum & i have had both lights apart & the build quality looks better on the viperspectra. it has 420nm mars has none, & 12k white, mars runs 10k.