It doesn't really matter which one you buy, they all have the same amount of difficulty when installing them. So just buy one that has the features you want at the price you can afford. When you remove the old radio, you'll notice that all the wires go into a plug, which simply plugged into the factory radio. This plug will not plug into your new stereo. DO NOT cut this plug off. You can buy an adaptor harness for about $7 that will let you plug the new stereo into the factory plug. It makes the stereo 1000x easier to install.
According to crutchfield.com, you have 6.5" speakers in the front doors and 4" speakers behind the seats if it a regular cab, or if it's a super cab, it's 6x8" speakers in back. Just make sure your new speakers are those same sizes and they'll be easy to install too.