I used to use etfconnect before they went paid and started concentrating on closed end funds. These days my source of information is spread out. The primary source about the instrument (ETF) itself is etfdb, backed by information from Morningstar and Yahoo Finance. For comparison charts Google Finance can't be beat. For actual solid details about a specific ETF, would check read the prospectus from the managing firm itself.
One other comment, never trust a site that "tells you" which securities to buy. The idea is that you need sources of solid information about financial instruments to make a decision, not a site that makes the decision for you. This is due to the fact that everyone has different strategies and goals for their money and a single site saying buy X sell Y will probably lead you to lose your money.