My favorite slip-on for looks is the turndown - aka Streetsweepers.. I have V&H Streetsweepers on my 07 Roadking.. look good and sound awsome..

 

V&H fishtails, great look for my scoot and the sound is just right

 

Screamin Eagle Pro Slipons 65115-98B these are the best, and Supertrap now sells the same product. However the new SE thunder is a newer version available from HD 65115-10 May be close the the same. Either way get rid of the cats in the head pipes.

 

Klock Werks SS-nice low rumble at idle Good bark when you get on it

Somson fishtail drags - when I want to make some noise( and loose some bottom end tourqe, lol)

 

Bub 7's. Nice deep throaty tone not too loud. Like slash up's but there reversible too.

 

My top three would be:

V&H Ovals
V&H Basics
Samson fishtails (straight with baffles not the necked down versions)

currently have the Samson's on and love the look of the bike. A little souder than the V&H options but I like it.