Tor is not a good VPN for me and I've been having consistent small Internet anytime I tried using it. Tor has been knows and a reliable free VPN app to use but I don't think it works for everybody. Orbot has been a good VPN
Although both tor and VPNs are used mainly for the same reason which is improving user’s privacy, they are not the same. Tor is not a VPN, so it’s inappropriate to compare it with Orbot or any other VPN.
However, accessing websites using tor browser is usually slower compared to accessing them via a VPN especially if it’s a paid one.
For better privacy and if latency isn’t a big concern for you, you can use tor over VPN.
In this time and age that people are usually in a haste to get things done really fast to enable them move on to the next one, I highly doubt any one will be comfortable using Tor as a browser specially the mobile version, since this seems to be way more slower than the desktop version of the app.
Orbot, on the other hand is a VPN app that is developed by the same developers of Tor, and they both works flawlessly together, I personally I have tried the combination of this two and it did provide a top notch security and privacy, but then, speed was a big issue, at the end of the day, I ended up frustrated and had to delete Tor first, and later on deleted Orbot when the VPN made my internet so slow to the extent that sometimes, I will be getting a connection error.
In conclusion, if speed is one's priority in using VPN, then orbot is definitely not worth a try at all, it's the best VPN app, but still, the worst when it comes to speed.