The good ones are usually AES encrypted. Split tunnelling on top and you are as safe as can be with current technologies.
Taken from a well known quality VPN which does not keep logs and is registered in a country that does not subscribe to the 'five eyes' agreement.
Besides hiding your IP address and mixing your traffic with that of other users, XXX VPN also encrypts your traffic between secure VPN servers and your computer, so that it can’t be read by third parties in between, such as your internet service provider or your local Wi-Fi operator.
XXX VPN uses AES (Advanced Encryption Standard) with 256-bit keys—also known as AES-256. It’s the same encryption standard adopted by the U.S. government and used by security experts worldwide to protect classified information.
256-bit keys means 2^256 or 1.1 x 10^77 possible combinations. That’s 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,560,000,000,000,000,000,000,000,000 combinations! A brute-force attack on a 256-bit keyspace is simply infeasible, even if all the world’s most powerful supercomputers ran for as long as the universe has existed so far, billions and billions of times over.