Neither guitar is better or worse than the other. They're just different versions of the same instrument. Both are tuned the same way and have six strings.
Here are some of the main ideas to think about in making your decision...
1. What kind of music are you interested in playing? Death metal, punk, and rock? Go for the electric. Classical, delta blues, or country? An acoustic is probably a better choice.
2. Do you want to start with the easiest or get the hard work out of the way at the beginning? Acoustic guitars are a little harder to play due to the factors I'll explain below. If you'd rather put the work in at the beginning, starting on acoustic and moving to electric later is very easy. Moving from electric to acoustic takes a little additional work.
- Builds better hand strength
- Encourages better tone because you're not being helped by technology
- Thicker strings can be harder on your hands and fingers until you build up strength and calluses
- While rather quiet, it can't be played silently (a concern for apartment dwellers)
- Lighter strings are easier on your hands and fingers at first
- Can be played silently if your amplifier has a headphone jack
- Not as much hand strength needed
- Moving to acoustic afterwards can be harder as you'll need to increase hand strength
- Reliance on distortion and effects can make for sloppy technique
- Need to learn more muting techniques to deal with amplified sound
Personally, I started on acoustic guitar. A really terrible, difficult to play one too. I moved to electric later on and still play both regularly. As I mentioned, the transition from acoustic to electric is easy. The transition from electric to acoustic usually means having to tone up your hand muscles a bit before feeling comfortable. You'll also need to get used to the larger body of an acoustic guitar.
If you do start on electric guitar, make sure to practice a lot without distortion and effects that mask sloppy playing. Playing clean will help you catch stuff you need to fix. Go ahead and use those effects when it's time to rock though.
The decision to start with acoustic or electric guitar depends on your goals as a player and the type of student you are. My suggestion is starting with acoustic guitar, but your own goals should be the deciding factor.