I guess even if every manufacturer were to start making electric cars, I would still buy a Tesla. In my opinion they seem to be the first actual electric car company that made it and frankly if you go with someone who invented the first compelling long distance car you can't go wrong. Unless Tesla stops innovating or progressing why own another companies vehicle if what you are looking for is the definitive made electric vehicle.
Tesla has a lot of "We were there first" potential. I can't explain it, but other companies just end up looking like copy cats or individuals who are playing catch up. Tesla seems determined for quality as well, which gives them huge points. Their CEO is sincere about said quality where you get the feeling other companies are sincere about their bottom line.