lol ASUS is a multi-billion-dollar global OEM,
Wikipedia says ASUS is primarily in the industry of "computer hardware" and "electronics", with a range of products including "desktops, laptops, netbooks, mobile phones, networking equipment, monitors, projectors, motherboards, graphics cards, optical storage, multimedia products, peripherals, wearables, servers, workstations, and tablet PCs". Wikipedia doesn't say much about ASUS involvement with manufacturing, research, engineering, subsidiaries, technical services, outsourcing, insourcing, logistics, marketing - which, given ASUS's worldwide (and sometimes world-leading) scope of operations, are basically mighty mini-industries in themselves.
Who is ASUS's all round biggest rival in the whole industry? ASUS has many rivals in many industries. You'll get different answers and different "Top 10" lists from Gartner, BusinessWeek, and PCWorld; different "Awards" from London, Hong Kong, Wall Street, and Taiwan market analysts; you'll even get different answers from ASUS's own online media in different countries, each emphasizing the products and interests which appeal most to their local markets. Your question is simply too broad, vague, and nonspecific - it cannot properly be answered in any meaningfully absolute and specific context.
Here on the ASUS ROG Forums we're largely interested in gaming and overclocking. So the products we know best are things like gaming motherboards, gaming graphics cards, gaming monitors, gaming laptops, gaming keyboards and mice. And we're most interested, of course, in ASUS ROG products - partly because this forum is provided and paid for by ASUS - but also very much because ROG gear is quite often the very best of the best stuff available. ASUS isn't a perfect company by any means, it has plenty of faults, but ASUS tech is consistently high-quality, high-reliability, and high-performance - ROG-branded products in particular have a focus on pushing thresholds with innovative gaming and overclocking technologies.
Pick an ASUS product, go to whatever store sells it, and see what other companies sell competing products. Go online and start comparing ASUS products/services to competitor products/services. That's probably about the best answer you'll get (and have been given) around here unless your question is specifically related to things we know like gaming, overclocking, ROG wares, and ROG-competing wares.
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