It's probably worth noting that the third one you listed, HMA, was recently cooperative with a US investigation into Anonymous. You should check the log retention and other policies of whatever VPN you choose to make sure they are suitable for your activities. For example, if you are traveling in a country with restricted Internet access and accessing confidential information from your employer's network, you probably don't want to be using a VPN service that cooperates with requests that may be harmful to your employer.