I have a plain, flat leather collar that I've been very happy with.
I got mine from http://www.gundogsupply.com and have been really happy with that company as well. They have a very nice selection of leather flat collars, starting at FIVE dollars for the "field grade, oiled-leather" ones. All their leather collars have an option to get a free brass plate with your dog's information added to them, too.
I have a couple flat collars that I like. I might have the Amish guy make me a couple of rolled ones too. I have 90% of my dog leashes, collars and harnesses made by the local Amish. Price and quality are second to none.
They are maybe a little pricey, but unless Kodee has a tremendous growth spurt, the one I ordered for him a few mos ago (I bought it fairly big, and it fits great now, with 2 or 3 notches left for growing) will be the only collar he ever has. I also have the 18" traffic leash, a 4 ft. leather leash, and 6 ft leather leash, all to match (all from Leerburg). The leather is very thick, but really soft, and these are stitched AND riveted - most places only do one or the other. They are also handmade by the Amish. I use leather cleaner and then leather conditioning balm on them about once a month, which keeps them looking and feeling new.