In my humble opinion and experience, nanos (10+ gals) are easier to setup, maintain, control, and correct if something goes wrong. They require a lot less time and money to do all the above.
Evaporation (what most people think is one of the biggest culprits in parameter-swings) is really not that bad especially if the setup has a top (a cup every few days).
Additionally, along the lines of Enigma's post above, the more "toys" you add to your setup, the more fidgeting you will have to do regardless of the size of the setup
The simpler it is kept, the less things you can play with
I truly think the biggest issue that hurts the new/beginner aquarist is not tank size or equipment, it really is husbandry knowledge (or lack of). Also knowledge of how much your tank size can handle and what it can and cannot do based on the included components.
All that said, nanos are also VERY limited in what you can keep in them. Most beginners are after tangs and angels, and have a stock-list that can only be accommodated in a 200+ gal tank!!!
My 2 cents.