<prompt> Human: I was wondering if anyone had any experience w vanguard vs. ishares etfs. It seems like Vanguard ETFs seem to have a lower expense ratio, but ishares tend to have smaller bidask spreads. Anyone know which is more important for longer term investments? Thanks for your help!  <response>: You really cant go wrong with either for the core index ETFs, but the board here generally favors Vanguard. iShares has much more specific ETFs that let you customize to a very fine level if you desire. iShares new core line of ETFs total market is comparable to Vanguards total market ETFs but there are some differences. - iShares generally have fewer holdings in the funds which can lead to some small differences in performance can be better or worst. - iShares total US stock follows a different index SP1500 vs CRSP which should hold fewer stocks in excluding the smaller cap companies. - iShares total international and total bond currently have a tad lower ER than Vanguard, although I would check what the volume and spread of IXUS total international is.- Vanguards total US international stock funds have much more unrealized appreciation than iShares. Although this point is usually moot because these are ETFs and total market funds, but it is still a small risk Vanguards VWO has to liquidate all of its Korean holdings with the index switch and may possibly realize capital gains as a result. 