Big is easier but more expensive. Check out the nano forum - the industry now caters to smaller tanks with great features like built in sumps with compartments that can be used as refugiums, house skimmers etc. Folks like live aquaria sell "nano packs" for corals and clean up crew.
LEDs compliment the artistic decor of the "nano cube".
With nanos, less is more. a pair of clowns, a few pieces of rock, a couple of corals and some use of empty space can be very dramatic.
That being said, do a nano because either that is what you really want or if you are limited in space and can only fit a nano. If you are starting small because you want to put your toe in the water and make the transformation to salt water, you'll quickly want to upgrade - and even though nanos are not as expensive as large tanks, they are not cheap as to make it economical to be considered them starter platforms.
I have a 29 gal - my first attempt at saltwater. It's a basic tank (not a cube or specialty nano). It's all I can fit in my living room. It's a vanilla reef tank, a bit over stocked. Being over stocked (not from design, but rather from lack of expertise) I run a 5 gal HOB cheato packed sump, biopellets and GFO reactor and a skimmer. While I love my tank and how it's developing. Had I been able to fit a larger tank in my living room, I'd be looking to upgrade as I type and seeking to recoup pennies on the thousand+ dollars selling all the nano hardware. I also, wonder, knowing what I know now, would I have opted for a more dramatic look of a minimalist nano cube. I don't know.
I do read more and more posts from "tweener" tank owners like myself - 30 - 90 gals give or take - tanks that some nanoist think are to big to be a nano, but traditionalist would advise against as being too small. We are proof that these tanks can indeed keep reef life successfully.