Serebii is the best general-purpose one. Finding movelists/egg lists/whatever is painless, easy to read and doesn't take long. It still looks like something out of the 90s, but that's not a bad thing when it's the fastest and easiest one to find anything with.
Bulbapedia is generally more accurate and complete but the layout of the articles absolutely sucks from a readability point of view and navigating/finding specific information is a nightmare. Really, they should separate the game-based information from the anime/manga/whatever information. It's a complete cluster.
Smogon is useful if you want basic singles movesets/spreads. Which I usually don't.
www.warsworldnews.com - Wars World News - The most chilled AW community on the web.