Lightning doesn't really 'go for' anything in particular, but rather is just trying to release a buildup of electricity as quickly and easily as it can. The interesting thing about it, is that when it is progressing down from a cloud, it chooses the 'best, easiest, quickest' path in 50-meter increments, almost as if feeling around a fog. By the time lightning flashes, you may see a pretty crazy path in the sky in all sorts of directions, sometimes hitting the highest point on the ground, sometimes not. Lightning can go in loops, can move horizontally a long ways before striking downward-- just about anything is possible. Since all of it happens in a fraction of a second, you usually only see the result of all this incremental decision-making.

Now...as far as the 'going for water' part...We're really only talking about water once it has been struck by lightning. Water on the ground is no more likely to be hit by lightning than dry land. Water, however, does something called 'conducting' for electricity. This means for water, electric current will flow through the entire body when struck by lightning. This makes being in water during a thunderstorm VERY dangerous, because you yourself do not need to be struck by lightning to be electrocuted, as any part of the body of water you are in would just have to be struck for the current to make it to you as well (through conduction).

Now, don't freak out when you go swimming in the ocean, because indeed it is true that lightning is striking the ocean just about ANY time you have ever dipped your toe in the water. However, on average the electric charge is dispersed through so many miles of water before reaching you, it isn't a problem. A good rule of thumb is the presence of thunder; When you can hear thunder, that is a solid indication that you should not be in the water anymore (and should head inside).

Another note here...Metal conducts lightning just like water, which makes for some interesting discussions. However, just like water, lightning is no more likely to hit a flag-pole made out of metal, than a telephone pole made of wood, should they be right next to eachother.

The material of composition can't add or subtract attractiveness to lightning in the least...But rather the conversation squarely rests in 'what happens next' once lightning strikes something that can conduct a charge across its surface.+