It depends on what you're doing, if it's complex routing there's four companies out there (for me) Cisco, Juniper, Foundry and Force10.
For switches the same companies, plus Extreme Networks and 3com.
For voice, if you've got the tech to do it, nothing comes close to Asterisk, and just go with whoever's phones are better for you, from Snom, Linksys, Cisco, Polycom, etc. (or a combination)
For wifi there's others.
Generally if you have good staff taking the step above the D-Link / netgear / linksys / whatever gear is worth it.
Also remember that most of the "top shelf" Cisco competitors are cheaper and often have a better product. Personally I find Juniper gear far better at the same pricepoint, but it's really aimed at the ISP market.
If you're a HP shop I know several fans of the HP switches, but also several haters.