My advise? Don't waste your money with the Horse Master, he'll take two weeks to get you a thoroughbred horse with the same stats as one you could've just bought from the market place.
Statistically the best armor is the Hand Crafted Black Armor if you like to ride horses, as not only does it provide great torso protection, but gives the best leg protection out of all the armors available. Also the best helmet is the Hand Crafted Armlet. It's a closed helm, requires 14 Strength I think. Looks a little odd for a marksman.
Now for guns... the Double Barrel Dutch Pistol is pretty epic. Good accuracy, good damage, it can be reloaded while running if you're on foot (like all pistols) and can be fired from horseback. The most accurate weapon is the Hand Crafted European Musket, something like 97 accuracy. Awesome damage too, only surpassed by the Hand Crafted Turkish Musket in damage I believe. Of course the downside is the muskets can't be fired from horseback, and you have to remain stationary to reload them.
I'd skip the Hand Crafted Double Barrel Carbine, it has worse accuracy and damage than the Double Barrel Dutch Pistol. I'd also skip the Hand Crafted Dutch Pistol, as it seems bugged... it seems to be using the double barreled pistol reload animation, so it's taking twice as long to reload as it should. If you do want a carbine though, it's hard to go wrong with the Hand Crafted Carbine. My favorite pistol so far is probably just the Hand Crafted Pistol. Not as spectacular as any of its contemporaries in damage or accuracy but it has the fastest reload time. (The "Reload Rate" for the double barrel pistols is higher, but remember it's reloading two barrels, so still takes longer.)
Finally the best sword I'd say, the Hand Crafted Broad Sword, excellent cutting and stabbing damage. Its appearance is the same as the Scottish Broad Sword.
Also, it doesn't matter what town you order these from.