Undecided?

So I'm really into Pico tanks right now. I'm looking at the TOMs deco kit, and am pretty sure that's the one for me. Only thing is, I'm not sure whether to make it a small betta tank (only thing that worries me is the open top) an endler tank, or a Pico reef. I'm not so sure about the reef because I'm still just getting settled with mine after lots of work, and I'm not sure if I'm ready to do it on such a small scale (it's more work I've heard?)

Suggestions for either proposal?

Oh and the FW would be planted

 

ive done picos, while beautiful there is daily top ups required. if you have an ato then no worries. but other wise probably be topping up everyday

 

whats a good ato unit for a tank that size? 3 gallons