There does not appear to be much difference in the management of the mutual funds I have exposure two between the two companies...the Oppenheimer funds don't generally achieve any greater returns than the equivalent Vanguard funds. Vanguard is owned by the shareholders, and therefore, keeps their costs lower than most other firms. If the net return is greater, than paying more might be worth it, but I haven't seen this to be the case...you'd need to make ~1% greater return to justify the cost.

Sorry, I lost the context of this question. In Vanguard, my mutual funds have expense ratios of 0.04% to 0.18%. It total, annually, I 'pay' about $800 in fees to Vanguard. If my expense ratio was more typical of other firms, or more actively managed funds (say, 0.75%), then I'd be paying about $9,000 annually. My mom has an Oppenheimer fund with an expense ration of 1.15%. If all of my assets were invested in this fund, I'd be paying nearly $14,000 annually, rather than $800. What matters is whether you're getting more return for higher expense ratio funds. This is often not the case. Expenses matter!