Many VPNs accept btc. However, if you want to stay anonymous, you shouldn't rely on VPNs too much. Use Tor, either by itself or together with a VPN.

When you are deciding which VPN to buy, look at reviews on deepdotweb.com, torrentfreak.com and other reputable sites. They have lists of vpns rated by important factors such as which country they are based in, whether they keep logs, etc.

From the top of my head I'd say mullvad, privatevpn, ivpn, privatoria are the best when it comes to anonymity. They all accept btc.

If you need a good anonymous vpn that has a free plan, try securitykiss, I think they give you 300 Mb/day for free.