With May just around the corner, now could be the perfect time for investors to review their portfolios and look for opportunities to position themselves for long-term growth.

And with global markets remaining volatile but full of potential, ASX ETFs continue to offer one of the simplest and smartest ways to get diversified exposure to quality companies.

If you're looking for ideas, here are three top ASX ETFs I'd consider buying in May. They are as follows:

iShares S&P 500 ETF (ASX: IVV)

The first ASX ETF to consider in May is the iShares S&P 500 ETF. It provides investors with exposure to 500 of the largest companies on Wall Street. This includes household names like Apple, Starbucks, Nike, Amazon, Tesla and Alphabet.

Despite short-term economic uncertainty, the US economy has proven incredibly resilient over time. The S&P 500 remains a benchmark for global equity performance, and history shows that investors who buy and hold through the inevitable ups and downs are often handsomely rewarded.

Overall, the iShares S&P 500 ETF could be a great way to tap into the world's biggest and most dynamic economy, offering a strong blend of defensive blue-chips and high-growth leaders.

VanEck Morningstar Wide Moat ETF (ASX: MOAT)

For those who want a more selective approach to US equities, the VanEck Morningstar Wide Moat ETF could be a top option.

This ASX ETF focuses on fairly valued US companies that have durable competitive advantages — or wide moats — that can protect profits and market share over the long term. These moats could be built on brand strength, cost advantages, network effects, or intangible assets.

Its current holdings include companies like Microsoft and Walt Disney, which are leaders in their fields and have business models that are tough for competitors to disrupt.

By concentrating on quality companies that are trading at attractive valuations, this fund aims to deliver long-term outperformance with a bit of built-in downside protection.

In an environment of rising uncertainty and slowing economic growth, focusing on companies with real, sustainable advantages arguably makes a lot of sense.

Vanguard MSCI Index International Shares ETF (ASX: VGS)

Finally, the Vanguard MSCI Index International Shares ETF could be a top pick for investors in May.

This ASX ETF gives Australian investors broad exposure to global developed markets, covering the US, Europe, Japan, and more. It holds over 1,400 companies across multiple sectors and geographies, offering incredible diversification in a single investment.

For anyone wanting a true buy and hold core holding, the Vanguard MSCI Index International Shares ETF could be a fantastic option. It captures the power of global growth while smoothing out country-specific risks by spreading investments across multiple regions.