CAMBRIDGE, Mass. — Rite Aid Corp. and BJ’s Wholesale Club Inc. were the biggest gainers among food, drug and mass retailers in Forrester’s U.S. 2017 Customer Experience Index (CX Index).

The index, based on a survey of some 120,000 U.S. online adult consumers, measures and ranks more than 300 U.S. brands across 21 industries. Of the 315 brands ranked this year, 36 traditional retail banners were analyzed to gauge how consumers perceive their shopping experience — both in-store and digital — and how that perception drives ­loyalty.

Among retailers, PetSmart Inc. was No. 1 overall in customer experience for 2017, followed by Nordstrom Inc., Hallmark Cards Inc., Neiman-Marcus Co. and Hobby Lobby. BJ’s was first among food, drug and mass retailers, coming in at No. 6 — up from 15 last year. The warehouse club operator edged out No. 7 Costco Wholesale Corp. which saw its ranking slip a notch from sixth last year. Rounding out the top 10 were Bed Bath & Beyond Inc., Michaels Stores Inc. and Ikea.

Rite Aid saw the biggest improvement in the food, drug and mass arena, climbing from No. 31 in 2016 to 18th this year. Rival drug chain Walgreens moved up to 11th in 2017 from 14th last year, while CVS Pharmacy dropped to 21st this year from 16th in 2016.

Walmart rose three spots to 35th, while its Sam’s Club warehouse chain dipped two places to 13th. Target Corp. fell one spot to 24th, and fellow mass merchant Kmart rose one spot to 36th.

Forrester found that the average score declined by one point this year. “Rite Aid is the only brand that saw a significant increase, which was less than half of the biggest decliner’s decrease in 2017,” the research firm pointed out.

The top emotions driving customer loyalty in traditional retail are feeling appreciated, respected and valued, Forrester noted. “For example, 91% of customers who feel valued plan to stay with the brand, and 89% plan to spend more,” the firm explained. “This proves that emotion affects retailers’ bottom line: a one-point improvement in a CX Index score can lead to an incremental $244 million in revenue for big-box ­retailers.”