There are always a ton of threads about motors and ESCs and they are all usually variants on the same questions. In this article I will go through and explain the basics of choosing a motor and ESC/MSC, and talk about brushed vs. brushless systems.
When choosing a motor it is important to choose one that meets your abilities and budget. The first thing to consider when buying a motor is how fast you realistically want the car to go. I know you all want your cars going 50mph, but there are only a few of us who have enough driving experience to go that fast without hitting straight into a wall. The basics on turns and winds are as follows:
Lower Turn = Higher Top End/Less Torque
Higher Turn = Lower Top End/More Torque
As you look at motors with lower winds, you begin to see motors like a 9x3. This means that the motor is 9 turns and has 3 winds. The winds are simply for more speed, the more you have, the faster you go. One thing to note about lower turn motors is that they need a lot more maintenance. You can probably run a stock motor (27T) for 15-20 runs before it needs to have the commutator cut. On the other hand, a 9T motor needs to be cut every 3-5 runs.
There are a few classes for brushed motors:
Stock (27 Turn)
19T Spec (19 Turn)
Unlimited (Any amount of turns)
Your hobby shop or race track may have others, but these are the common ones.
Choosing whether to get an ESC or MSC is an easy decision. Get an ESC. MSCs (Mechanical Speed Controls) are very outdated and cannot handle today's motors.
When choosing an ESC you truly have to rate your skill level. While you may have a 19 Turn motor today, will you be changing to an 8 Turn motor soon? The answer is probably not. An ESC's limit is the lowest number of turns that it can handle. Now you have to make a big decision. Since ESCs that can handle lower turn motors are more expensive, you will have to decide how low you're gonna go. It makes no sense to buy an ESC with no turn limits if you are going to race Stock and 19 Spec, nor does it make sense to buy an ESC with a 17T limit if you are going to race Unlimited. This is basically up to you (and your budget), but be reasonable and get an ESC with a limit that is around your skill level.
My final rant will be on brushed vs. brushless. While these systems are in relatively the same price range, they each have their own pros and cons. A brushed system needs a lot of maintenance, but offers more flexibility because you can change motors depending on track conditions (how much torque you need). A brushless system on the other hand, needs almost no maintenance.
There are two basic decisions you need to make when buying a brushless system. How much can you afford to spend and how many transmission gears you want to replace. The Novak systems are more affordable, ranging from about $180-210 and include both a motor and ESC. The next level up would be a Warrior/Feigao combo which will be about $250 and will have more power and a nicer ESC. The highest level of brushless are the Hackers, Lehners, and Shulze. These are not for novices, and must be geared almost perfectly. These systems can range from about $400-800 for just a motor and ESC. Also note that the Novak and Warrior/Feigao combos offer better customer support and are easier to get.
I hope this article has answered most of your questions about motors and ESCs. Good luck, and have fun!