A winch is a very important item to have on your vehicle when you go off-roading, and for those who regularly drive in mud, snow, sand, and the like. Without a winch, you might get stuck in an area that even a tow truck cannot access, and it can mean hours of work digging out your vehicle, not to mention a lot of expense! When you are ready to buy a winch, note a few factors to consider so you get the right choice.
The capacity of a winch is called its rated line pull. When choosing a capacity or pull, remember that you don't want to choose just by the weight of your vehicle alone. When stuck in mud or sand or elsewhere, you're getting drag on the vehicle that the line will need to overcome to pull you out. It's good to choose a rated line pull that is at least half over again the weight of your vehicle, and increase this even more if you drive in very thick mud or on another surface that will mean even more drag or resistance on the line.
Don't assume that the longest length from your winch is the best choice; remember that the longer the line, the larger the spool on the front or back of your vehicle. This can be unsightly and interfere with everyday driving and parking. Remember that letting out too much line will mean losing tension and strength, and the more you let out, the more likely it is that the line will get pinched or jammed as you try to recoil it. It's good to just get a decent line length and then, if you do get stuck when off-roading, position the recovery vehicle close enough to your own vehicle to get you out without relying on an overly long line.
Typically you can choose either wire or synthetic rope for your winch. Wire may be less inclined to cause abrasions than synthetic, but it is more likely to get scuffed and torn. You may see individual threads or small wires come loose from wire rope if you regularly pull heavy vehicles with the winch; eventually this will compromise the strength so much that the rope needs replacing. Synthetic ropes are also more lightweight so they won't weigh down your vehicle and, because of how they're composed, they're more likely to just fall if they break versus snapping back at you.