The only one I know of is Dennis Kirk in Rush City, MN. Here is their website. Used to live in RC, but not a routine customer there. Sometimes they have what you need, but more often they do not. High prices, odd selection, keep your options open.
DennisKirk.com is pretty good. Usually everything is at list price, but that is not uncommon.
Revzilla.com is pretty good, big selection, and usually lots of stuff in stock. They ship quick. They have a sister website Cycle Gear, same prices, same everything.
The little guy in the industry, that is also pretty good is motorcyclegear.com They sometimes have better prices than the others, but not always. I tend to compare prices. If I can, I buy from motorcyclegear.com.
For most items, if you compare prices, the price may vary by a couple of pennies as there seems to be manufacturer's agreements on minimum prices. If you want a deal you need to buy discontinued items and overstocks. There are a couple places that specialize in discontinued items and often have deals on lesser quality brands.
There are others, some specialize in more HD realated stuff. Others specialize in more offroad/dual sport/ADV touring stuff. But the 3 listed above will get you well outfitted and supply lots of stuff you didn't know you needed.
Sometimes you get lucky and get something like an Arai or Shoei or Schuberth helmet for a couple hundred dollars off, but it is usually an unpopular graphic or a discontinued item. Still top quality, and a great deal IF it fits.
For jackets and pants I prefer Rev'it, which is a Dutch brand or KLIM which is an American brand. FirstGear is a good modestly priced brand, but they have very limited designs and it seems like I'm seeing far lower availability over the past couple of years. Rev'it, Klim, Dianese make top quality PROTECTIVE gear and high prices. Dianese seems to make a lot of slim (European) cut clothing, which just doesn't fit me, but it is good stuff. Rev'it and Klim fit me. Boots from Sidi, Forma, Rev'it, Dianese, Alpinestars and several others are usually good. Forma being the discount brand of that group, but still good. Usually can find deals on many of these brands.
I seriously dislike Joe Rocket, Tourmaster, First Manufacturing and several others.
When you start shopping for gear you should think about what level of protection you want. Start from that point. It will allow you to eliminate some items and narrow you choices.
For example, the majority of "touring boots" have no protection for the shins. If you want shin protection that will narrow your list.
With jackets or pants you need to look at armor and material. Many brands never test their clothing, they just stuff "CE armor" in their clothing and never tell you that seams are prone to fail. So I look for clothing that has been tested. Most of the European brands and Klim do that, their clothing must be rated "A" to meet the minimum standard to use in Europe. "AA" is considered excellent protection for street wear. "AAA" is required for race gear. I have a couple piece rate AA but most of our stuff is simply A rated.
I have 4 pairs of moto pants. One made of serious mesh for hot/humid weather. One of Gore-Tex for rain/cold. 2 of heavy canvas like material for casual riding in most weather. All have hip and knee armor. One is AA rated, 3 are A rated. For jackets I again have several, to match weather, and again, one is AA rated the others A rated. I've upgraded most of our back armor to CE level 2. Many brands come with CE level 1, which is probably sufficient. Some jackets, even from top brands, only include a thin piece of non-protective foam and you must add your own armor.
Gloves for motorcycles are designed very differently than garden gloves. Reinforced palm 'sliders' to save you from skin grafts on your hands if you ever skid. Knuckle protection to minimize broken hands. 2 of my pairs even have little squeegees to wipe rain off my visor shield.
And "armor" is a strange thing. It looks like simple rubber. Some is. Some is pretty high tech and changes its density under pressure to spread the impact across a wider surface.