If your connection goes like this: VPN -> Tor -> Internet
then your ISP can only see encrypted data and assume you use a VPN but it can
not know whether you are using Tor or not. The main advantage of connecting
to Tor behind a VPN is precisely to hide its usage to the ISP. Now, Tor is
not illegal but it certainly attracts a lot more of attention than a VPN.
Another good point of connecting first to the VPN and then to Tor would be in
case a global adversary manages to control both the exit and the entry node
of a given Tor circuit, in which case the entry node would see the IP address
of your VPN provider and not your ISP's one. The downside though is that the
vast majority of VPN providers do declare not to keep logs but you can not
know if that is the actual case and you should assume that they do indeed
keep logs (metadata - ip addresses, time of connection, webpages you
connected to) so .. choose well if you are going the VPN way..
cheers
