Worth noting .... IndependentInvestor.info has published an article that pulls together various official media sources of recent discount broker comparisons and ratings. There is an especially useful link to a pdf table compiled by a finance student Charles Martineau which contains direct links to the specific sections of the broker websites to get the detail on such things as commissions, account charges, dividend reinvestment policies etc.
Missing from the Martineau pdf are some other comparison factors that are significant like the ability to hold USD foreign currency in registered accounts and/or the implicit commission rates charged by brokers who do not allow foreign currency in such accounts and; for ETF investors, the ability to DRIP, which may not work as easily as for ordinary shares, as I posted about in DRIPing ETFs in Canada.
The information makes clear that there may not be any single "best" broker for everyone since what is important to some, like low trading commissions, may not count for much to someone who needs good customer service or the best DRIP program. Or, as Independent Investor notes, it may that a broker like TDW has the best choice of fixed income. Indeed, the ratings surveys by the Globe and Mail, JD Power and Surviscor come up with quite pronounced differences in rankings.