I can't find 1 I like, its such a struggle getting equipment suitable for a nano reef setup. I'm looking in to lights with more power now for my corals as I only have a 6 watt. The main struggle I'm having is finding one that has a good mounting system I have a 15 gal.
Here's a good compact light for smaller nano tanks. This one comes with the gooseneck to mount on the rim/rimless of your tank.
From my own personal experience.
I transitioned from Freshwater to Saltwater and tried re-using lights for my reef set-up. It only works if you have extremely low-light demanding corals (this is based upon that the depth of your tank is 12") If your tank is deeper you need a better light to penetrate to the bottom of the tank, otherwise the corals will get nearly no PAR and it does not work.
When you step into intermediate corals you will want a solid light otherwise your corals simply won't thrive. Yes, it will survive, but not thrive.
My advice is to not skimp on the light and get a good one right out of the gate, so you don't have to re-buy. I learned this the hard way.
Other lights that are good for nano tanks >20 gallons:
AI Prime HD
Aquamaxx Nemo Light.
I am currently using a Current Marine Orbit LED light and it's just okay... I don't see it handling anything more than LPS corals, especially now that I have it on a mounting bracket (this increased the distance from the light to the water by 5", which means less PAR being distributed to corals underneath). Like I said, I spent $130 on this and all I can say is... it's okay for beginners.