You owe it to yourself to pitch your game to as many different publishers as possible. However, you should also realize that all publishers are not the same. Some work with definite genres, platforms, or budgets, while others seem to be scattered all over the shelves.
Before you approach a publisher, make sure that your title would fit with their repertoire. Research titles they've already published, and ask them where they'd like to concentrate their efforts in the future.
In addition, play some of their games. This not only gives you a clever excuse to play more games, but also could give you a good sense of whether the publisher is right for you. Also, even though this should go without saying, buy the games or have the publisher give you some evaluation copies.