When it comes to purchasing computers, several retailers are renowned for their wide selection, competitive pricing, and excellent customer service. While specific preferences might vary depending on your location (global vs. specific countries like the USA, UK, Canada, etc.), the following merchants are widely recognized and popular among consumers for computer purchases as of my last update:

1. Amazon – Amazon is a global giant in online retail, offering an incredibly vast selection of computers from virtually all major brands. You can find desktops, laptops, gaming PCs, workstations, and more. The platform's user reviews and questions section can be particularly helpful for making informed decisions.

2. Best Buy – Best Buy is a leading retailer in the United States and Canada, known for a wide range of electronics, including a comprehensive selection of computers. They offer the latest models from top brands, and their physical stores allow for hands-on experience before making a purchase. Best Buy also provides excellent tech support through their Geek Squad service.

3. Newegg – Newegg specializes in computer parts and electronics and is a favorite among tech enthusiasts and professionals. It's an excellent place for building custom PCs or finding specific models of laptops and desktops. Newegg is known for its competitive prices, detailed product descriptions, and customer reviews.

4. B&H Photo Video – While B&H is best known for photography and videography equipment, it also offers a significant selection of computers, especially models geared towards graphic design, video editing, and other creative uses. Their expert advice and customer service are highly valued.

5. Micro Center – Micro Center has fewer locations compared to other big-box retailers, but it's a paradise for tech enthusiasts. They offer an excellent selection of computers, components, and accessories, often at very competitive prices. Their in-store experience is particularly praised for the knowledgeable staff and the ability to see and compare products firsthand.

6. Apple Store – For those specifically interested in Apple products, the Apple Store (both online and physical locations) is the go-to destination. They offer the latest MacBooks, iMacs, and accessories, with the advantage of expert advice, in-store workshops, and the Genius Bar for tech support.

Each of these merchants has its strengths, from vast selections and competitive pricing to expert advice and after-sales support. Depending on your specific needs (e.g., type of computer, budget, need for hands-on experience before buying), one of these retailers is likely to offer the best shopping experience for you.