Heidi's House (UES) makes a great ...
Not fancy, nor big but its beauty lies in the simplicity of the ingredients and prep.
Rough chopped ground sirloin and chuck (grass-fed if you care, I don't) seasoned nicely with salt and pepper and adorned with lettuce, tomatoes and onion.
At $13 it is a bargain and maybe a steal when a place like Minetta will charge you 17 for their signature eponymous burger.
Only downside is that it's on an English muffin, but I quibble.
Great for the solo diner as well.