When I buy ASX exchange-traded funds (ETFs), I always do so assuming I will be owning the investment for the long haul. That's why I usually go for index funds like the Vanguard Australian Shares Index ETF (ASX: VAS).

However, I also invest in a few ASX ETFs that aren't index funds.

With these funds, I hope to achieve returns that exceed what a market-based index fund can manage.

One such fund is the VanEck Morningstar Wide Moat ETF (ASX: MOAT). This actively managed ASX ETF holds a relatively concentrated portfolio of US shares. These shares are selected based on their perceived possession of a wide 'economic moat', the Warren Buffett term used to describe a company's permanent advantage over its competitors.

Buffett himself has stated that he looks for signs of a moat with his own investments.

This moat can come in many forms.

Some companies have powerful brands that attract customers to their products over the competition. Coca-Cola is a great example of this.

Others stay ahead by providing goods and services at prices that can't be matched. Woolworths Group Ltd (ASX: WOW) and Coles Group Ltd (ASX: COL) arguably have this kind of moat.

Another moat can come in the form of offering a product or service that customers find difficult not to use. Microsoft's Office suite arguably falls into this bucket. As do the toll roads that Transurban Group (ASX: TCL) owns.

Invest like Buffett with these two ASX ETFs

The VanEck Wide Moat ETF only invests in companies that possess these moats. We can see this in the MOAT ETF's holdings. These include Disney, Altria, Boeing, and Pfizer. All of these companies dominate their respective fields and are arguably difficult to disrupt. No one can match Disney's impact and presence in popular culture. Pfizer owns drug patents that are difficult to compete with. And it's pretty hard to start a rival company that can manufacture aeroplanes, as Boeing does.

MOAT has managed to hit an average return of 15.71% per annum since its ASX inception in June 2015.

VanEck offers a similar ASX ETF with the same methodology for shares listed outside the United States: the VanEck Morningstar International Wide Moat ETF (ASX: GOAT).

Some of GOAT's holdings at present include Universal Music Group, Budweiser-owner Anheuser-Busch InBev, and Reckitt Benckiser.

GOAT hasn't been around as long as MOAT, listing in late 2020. Since then, it has managed an average return of 12.22% per annum.

Both of these ETFs, MOAT in particular, have demonstrated that the methodology these funds employ can bring long-term success. That's why I invest in MOAT (and perhaps GOAT soon), and would recommend them to any investor looking for a quality ETF to add to their portfolios today.