If you have your heart set on a 400 series, the Intellicig Evo is probably your best bet.
I started on a generic 402 last year, then went to an Evo, and then a 501. The Evo was decidedly better than the generics, but if you're a regular smoker looking for an alternative, you'll either go through cartridges like crazy, or need to carry liquid around with you at all times. Oh, and batteries, too. Those batteries don't last too long.
To be honest, I'd skip past all of those, and get an eGo. No, they don't look like cigarettes (which was a big deal to me last year). But frankly, neither do the 400's -- especially when they're glowing blue.
But if you're really set on the look, you can't go wrong with an Evo.