Well, it is very much personal preference, but here's my slip-on story for what it's worth.
When I got the bike, I told the dealer that I would not be replacing the stock mufflers...I liked loud cars and bikes when I was 18, but that was 47 years ago and my tastes have mellowed with age. Having said that, after 2 weeks with the stock pipes, I had to agree that they DO sound like a sewing machine! Strangers would come over, look at the bike, say something like, "nice bike man, what does it sound like?" I'd start the engine and they would look at me funny and then walk away!! It just didn't sound like a Harley - Honda was more like it.
So began the search.
I really didn't want loud, I can wear ear plugs but my neighbors generally do not.
The parts folks at the H-D dealership finally understood. Parts Manager, Tim, said, "You want Screaming Eagle, 49 state legal, pipes." "We have a customer's bike in Service Dept with those pipes, bring yours around to service and we'll compare." Great! Like picking out stereo speakers - listen to one set, then listen to the second set. "What's on my bike now" I asked, "aren't they Screaming Eagle pipes?" "Yes" said Tim, "Screaming Eagle 50 STATE LEGAL PIPES. Can you hear what a great difference one state makes!"
Perfect (for me) sounds like a Harley (the potato - potato thing) yet not so loud as to be obnoxious, even to the South Park kids.
Went and got a TTS Tuner and ran the whole thing over to the local tuning Wizard, whom you know from these pages. He plugged a map into that sucker that makes it twice as quick and it runs 25 degrees cooler with the loss of only one MPG, give or take a pint.
Here is what they look like…


Good luck!