If you have not started using different browsers you definitely should. No one browser is the best at everything but that is not the most important thing. You are making Web pages and you have no control over who sees those pages and what browser they use. So you need to make sure your site works well in every browser.
Realistically you can't use every browser so make your pages as close to W3C standards as you can and then test them in the most common browsers. Don't forget browsers on different operating systems and on a wide range of computers including tablets and 'phones.
Also look into sites such as Browsershots and IETester.