Now, you might be asking yourself: Why are these horses special? Well, there are three main reasons: They are fast, they have the best handling, and they can be obtained as early as chapter 2 (for free, no less!).
The White Arabian: Lake Isabella
Where: Lake Isabella, at the top left/Northwest corner of the region. The White Wonder can be found at a partially frozen lake, so be sure to dress warm and be ready to merk some wolves or bears if any decide to step.
When: This beauty can be obtained as early as Chapter 2!
How: Once you arrive at the lake, trot around. Binoculars will be handy to confirm it’s the White Arabian (study the horse if you need to confirm its breed). You can also use the Call of Duty method of using a rifle as binoculars, just don't derp out and accidentally drop the nice horsey. It's recommended to approach on foot and calm it before mounting. I tend to throw a lasso around horses just to ensure they can't run off right away, but that may just be paranoia. Either way, hop on dat girl and break it. When you do, command your previous horse to follow you and make your happy way down the nearest stable to save your new main.
Pro Tip: If you biff it and the horse runs off, leave the area, camp for a couple of days, and try again so that it respawns
The Black Arabian: Saint Denis Encounter
Where: The city of Saint Denis.
When: This ebony mare can be obtained as early as Chapter 2!
How: This horse is obtainable for free via a random encounter once the player has unlocked the ability to visit Saint Denis, a city all the way to the right/East of the map. This encounter involves a random couple getting mugged by some low-life.
This encounter tends to occur at night (around midnight to 6 A.M.). There are varying reports of where the black Arabian supposedly spawns, such as by the Theater. I found that the most reliable is on the road between the "I" and "N" of "Saint Denis" on the map, however (pictured below).
Step 1: Witness the Mugging
You’ll see a well-dressed couple being mugged. In many versions of the event, the wife is shot, and the distraught husband carries her body to his horse—the Black Arabian.Step 2: Claim the Horse
Approach the horse calmly and mount it. The husband is too preoccupied to react, meaning you won’t get a bounty.Or, if you aren't a complete douche, merk the mugger and then steal the horse. This will involve extra steps, but the wifey won't biff it. Alternatively, put all three down and make off with the horse if you are going for a negative honor playthrough. This second option is less lame, but will probably involve you needing to make a quick escape.
Step 3: Stable It Immediately
Ride it to the nearest stable to customize it and throw yer saddle on 'er. This encounter only happens once per playthrough.
Pro Tip: Patience is a virtue. This encounter may take a while to crop up, but it will eventually. Give it time and just keep strolling past the hot spots. When I first did this trick, I found the binoculars useful so that I could look down relevant streets to see if the encounter had spawned so that I didn't waste time galloping paste unnecessarily.
For a short (30 second) video showing how this works, check out my favorite video on the subject from YouTube user superantonio!
Final Thoughts
Having a good horse is super important in a game that everybody refers to as "Grand Theft Horse."
Don't be a pleb, get yourself a mach-speed mustang as soon as possible!