A circular saw is an awesome power tool - no question. Every good workshop should have one - and don't rule yourself out if you're at the home improvement level. They cut out a lot of labor intensive work and nothing cuts as fast as what's often termed a buzz saw.
Before you buy - make sure you choose the one that best fits your requirements. A wood circular saw isn't going to handle concrete or some metals for example so save yourself time and money and select the correct model prior to purchase.
The five best selling circular saws are featured below. Each one is in the most popular category, selling by the thousand, plus they're all top value for money and highly rated overall.