What is your price range? I have a older version of this that I am happy with. You can flip the rear wheel to go between fixed and free. But it was 500 bucks.

Get a Dutch bike: a Batavus or a Gazelle. Or, if you’re in the States, there are some great companies in Portland, OR, building single speeds.

my friend just got a bike from Republic Bikes. I took it for a ride and it was really smooth, definitely worth the money. He got the single/fixie for $399 + shipping.
I thought it was cool that you get to color custom pretty much every part.

It all comes down to fit. I have a raliegh 29er singlespeed that is awesome to ride, but by ss standards it weighs a ton. The price was right, and the bike was so much fun to ride, that when the first one got stolen, I bought a second one that a friend found for me at a bike swap.

I got it for under $400 both times. The first was slightly used and the second was new.

Definitely get a 29er though. I have a 26 inch single speed also, it doesn’t roll over stuff as well and it’s not as fast as the 29er.