For the fifth year running, drug giant Merck & Co. led Fortune magazine's list of most admired corporations as experts emphasized old-fashioned corporate basics - research and development.

A savings bank, Goldome, was the least admired company in the list, released Wednesday.Fortune's ninth annual Corporate Reputations Survey of more than 8,000 senior executives, outside directors and financial analysts, showed that business experts are emphasizing product quality and corporate responsibility. In earlier surveys, quality of management was a prime factor.

The experts liked Merck best because of its powerful earnings growth and its commitment to research and development.

Fortune's sampling ranked 306 companies in manufacturing and service industries on a scale of 0 (poor) to 10 (excellent), based on quality of management, quality of products or services, innovation, long-term investment value and financial soundness.

Also, the judges were asked for their opinions on the companies' ability to attract, develop and keep talented people, community and environmental responsibility and wide use of corporate assets.

Rubbermaid Inc. bounced back to the No. 2 slot after a one-year hiatus in third place.

But the status of Philip Morris Cos. went up in smoke, with a dizzying drop from No. 2 to No. 79. The plunge stemmed from the giant conglomerate's switch of categories from tobacco to food after buying out Kraft in 1988.

Procter & Gamble Co. edged up a notch to No. 3, and Wal-Mart Stores Inc. was the only retailer to make the top 10, holding the No. 4 spot.

In the soft drink department, Pepsi-Co. beat out Coca-Cola Co. for the fourth year in a row, placing No. 5 with Coke close behind, No. 6.

The experts thought that Pepsi's long-term investment plan was its greatest asset.

The judges were not happy with the institutions that handle their money. Great American Bank was No. 305, Crossland Savings had a lock on No. 304 and Meritor Savings Bank was No. 302.

In a farewell shot, the executives picked two companies operating in Chapter 11 as big losers, Continental Airlines Holdings Inc., No. 301 and the steel company LTV Corp., No. 298.

The sampling showed that to stay on top, the most admired companies must be able to compete internationally. Procter & Gamble is growing as fast overseas as it is at home, with 40 percent of its 1990 sales gains generated by its international group. Johnson & Johnson, No. 8, is another leader in offshore growth.

Eli Lilly & Co. jumped from No. 29 to No. 10.

Time Warner, whose magazine subsidiary publishes Fortune, ranked near the middle at 162.