You -> VPN -> Dest is often better than nothing, but definitely can't be relied upon if you need actual anonymity. The VPN can see everything you do, the destinations can see that you always come from the same VPN, and you're probably leaving tons of other traces because you're not using Tor Browser. Note that this might in some cases be worse than nothing if you trust your VPN less than your ISP; for example, IMO Cloudflare's VPN is more likely to have its traffic analyzed en masse by the NSA than your native ISP's traffic.
You -> Tor -> Dest is better than just a VPN, but there are many known attacks which can be used against Tor, plus possible 0-days against the browser, so you can never feel 100% anonymous. Also, even if you treat Tor as perfect, it's really difficult to remain consistently anonymous; for example, you might via Tor use the same email address to order something shipped to you as you use to speak out against your oppressive government, and that's a link that can be exploited. Even though Tor is pretty flawed, being far behind state-of-the-art research, it's these non-Tor anonymity failures which almost always get people. This was the case for Ross Ulbricht, for example. As I always say: if you think that you're perfectly anonymous, then you're wrong. Think of even the best anonymity tech as a light bulletproof vest which will increase your survivability a bit, not as an impenetrable wall.
You -> VPN -> Tor -> Dest protects against certain attacks where Tor nodes are considered evil, but can totally screw you if your VPN is evil. It might make sense if you trust your VPN more than a random Tor node. The VPN acts similar to a Tor guard node in this case. In fact, it'd be most efficient if the VPN actually allowed you to use it as a fixed Tor guard node so that you don't have a useless extra node in the Tor circuit, but nobody does this.
You -> Tor -> VPN -> Dest is much worse than Tor alone because the VPN can link all of your traffic together, whereas with Tor you change your exit node constantly. (It's also difficult to actually accomplish because VPN software isn't usually set up to support this, and VPNs are often- & best-done over UDP, which Tor doesn't support.) What
would be useful would be if you could pay via blinded bearer certificates for access to a whole constellation of exclusive paying-only Tor exit nodes, but nobody does this, either... Anonymity research is pretty immature, but actually-implemented anonymity tech is far behind even what is known to be possible.