Both rates do require at least a basic knowledge of electricity, but it all comes down to what you really want to spend most of your time doing on the job. The AET's will obviously get a much more thorough training in electricity, but as nick89 said, the AMT's will learn the basics too. Don't let the wait times deter you. I waited almost 3 years to go to AET A-School, and the AMT list was 4 years, but I knew I wanted to go AET. In my opinion I would say that for getting a general aviation job the AMT's would have the upper hand, unless you wanted to work in an Avionics specific position.
In my limited experience I have noticed that if the AET's finish their work early for the day, they will usually assist the AMT's in whatever needs to get done. I think it is more common for the AET's to assist the AMT's in their work, than vice-versa. I can't speak for other aircraft, but I have worked on the C-130H and now the C-27J. The C-27 has an upgraded avionics package which is pretty nice, but the AMT's have nice Rolls Royce engines to work on, and they seem to have much more work on a day to day basis. This is still such a new plane and program that things are still being worked out, so that may change in the future.
There are both AMT and AET C-schools to attend. I don't know if one rate has more than the other but there are quite a bit for each. I have actually attended Loadmaster C-School, which is traditionally an AMT-only school. So it just goes to show that opportunities are there regardless of which rate you choose. I know people from both rates at my unit that have their A&P's.
Overall, I think your choice should be based off of what you want to spend most of your time doing on the job; 1) changing engines/props/tires, turning wrenches, getting your hands dirty, (mechanical work), or 2) chasing wires, troubleshooting, changing lightbulbs, replacing avionics boxes, etc. Don't forget it is possible to have an Electrical degree as an AMT, or a Mechanical degree as an AET, and having either would complement the job nicely, as would almost any other degree. Whatever you choose, make sure you do well in A-school if you care about which airframe/unit you will be at. Your class ranking will determine where you go.