Are you really dead set on a single cell light? Imho lots of people will not even remember to switch through modes on a light, so you want one that always comes on in the right mode whenever you push the button or twist it.
For twisties you are then basically stuck with single mode lights, I like the iTP a3 eos std edition, but that is definately 'keychain' category.
This is why I moved towards the E21, it's a great value budget light with a twisty head to allow for 2 easy to access modes.
If you want to stick with single cells then I would recommend checking out shiningbeam's range of upgraded Romisen RC-G2s, they're really nice well built lights for their price and should last a long time. Simple to use, and easy to appreciate.
The problem is that with these single cell lights running on AAs is that if you give them to someone they will eventually use alkaline batteries in it. While they may think duracell means top quality and the best they can get, they will end up with very poor diminishing output as the cell is pushed hard by the relatively inefficient boost circuits used in most budget lights.
Again, this leads me to recommend 2 cell lights, as the higher voltage makes it easier on the circuit and much better if they ever end up putting alkaline cells in it. Out of these, the E21 is the best of the bunch for efficiency, ruggedness and value.