This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
It depends on your requirements.
Apache is widely popular Server Software.
But several popular websites (like Youtube and Wikipedia) use lighttpd. Lighttpd doesn't have all features which Apache has, but it's known to be fast.