One approach is to use, or at least start with, the Schwab ETF Select List. This list highlights the best ETF for each category, according to Schwab, based on wide ranging criteria, including "...assets under management, length of track record, trading volume, bid-ask spread, tracking error of the ETF to its underlying index....." The investor considering this resource should read the one-page write up of the selection process. DIY Investor and the working guy carrying all the tools, likes the fact that the list "...excludes leveraged ETFs, inverse ETFs, ETNs, actively managed
ETFs, muni bond ETFs with underlying holdings subject to AMT, and unmanaged baskets of securities."
Test question: How fast can you find Schwab's recommended ETF for the telecommunications sector?
Disclosure: I am not affiliated with Charles Schwab. The information in this post is for educational purposes only.