We have used Vonage for 5 years for both home and office. We have no complaints and it saves us lots of money each month. They included features at no charge that AT&T was charging us for (voice mail, directory assistance, three way calling).
My wife’s favorite feature from Vonage: if dialing a number in your same area code you only dial SEVEN digits.
Oldest daughter works on a private ship in Europe. She uses MagicJack. It drops about half the calls, but as there are no cell towers at sea, the alternative is a Satellite phone and the cost is prohibitive.