Each year, Barron's publishes its ranking of the best online brokers. Barron's uses many criteria, such as quality of research, commissions, and customer service. It even ranks brokers based on how often one trades - which, for most people, is not very often. It also ranks brokers based on if one uses options or not.
I have used Charles Schwab as my broker for several years, and while their commissions are some of the highest, their customer service is excellent, so I don't mind paying the extra dollar or two for my semi-annual trades.
Fidelity won this year, and I especially like this part of the article: "Fidelity has made a concerted effort to go after the millennial market, including repackaging educational content onto its mobile site. There are 12 programs available now, with more being added monthly. The Planning and Guidance center is designed to allow customers to focus on the future, planning for any kind of goal from college tuition to retirement to taking a long vacation. Fidelity Go, the firm’s robo-advisory service, is clearly aimed at the younger set."
Whether you are looking for a broker for the first time or looking to make a change, check out the latest rankings - Barron's knows its brokers!