Also important is to setup outbound firewall (or other mechanism) so that if the VPN goes down, you don't spew your traffic over the open connection [1].
I don't notice any speed difference from daily usage over the last year. Large file downloads I task my NAS to download outside the VPN.
My purpose is only to prevent the ISP from collecting logs about usage, I don't expect it to have much effect if I'm targeted for surveillance and I'm fine with that. Who knows how ISPs will handle the data (we've seen targeted advertising and content injection in the past) let alone all the agencies with less than stellar security practices.
[0]: https://github.com/thomascannon/scripts/tree/master/vpn [1]: https://github.com/thomascannon/scripts/tree/master/vpn/vpn-...
Large downloads is a concern of mine. I downloaded 1TB over PIA this month and it was never a problem. I can probably do these outside the VPN though.
NordVPN is one I keep seeing talked about, so I'll be looking into them this weekend :)
Advantages of a service seem to be location switching, good apps, cheap, and IP mixing.
Disadvantages are that you have to trust them not to keep logs, and lots of Cloudflare captchas, and they would seem like a good target for being compromised by the government.