Why you should trust your VPN vendor more than your ISP is a question.
Fair enough question, we all have seen the free VPNs that got busted doing more spying than those not using a VPN... But a lot of VPN companies use privacy as a selling point and know ONE bad provable leak/spillage/trace/report will kill their ratings on the web (and their bottom line).... Some VPNs almost go overboard to prove they actually care about your privacy... with things like buying subscriptions with bitcoin/cash without them even knowing your name. They don't register personal data at all... They don't keep anything to even give the CIA/FBI... they operate in countries that don't allow the CIA/ATF/FBI to even attempt to get info and even if they did request it they don't have the info to give.
Usually the higher the price of the VPN the more likely they take measures to protect privacy. I have ran a few over the years and some I would never use again (TunnelBear - woke to the point of being vindictive). I have a buddy that used a budget VPN with a lifetime subscription for 5 computers, and he has had no problems, but I wouldn't trust it.
Name brands like Proton, NordVPN (fast), Mullvad (Good Browser too), Heck, Mullvad even lets you mail in your cash payment. But even mid-tier VPNs do a fair job if you are on a budget and not exactly doing terrorist activity. Avast and AVG are in the ballpark though they do lack in some aspects like not deleting your data right away when you buy it. Some record how much data you use, some keep records in the mid-tier ones.
I run a mid-tier VPN, that has a good encryption. I can usually find a subscription for a couple of years for 20.00 or so. I need a "kill switch" that stops all internet if I get disconnected... I like "wireguard" protocall connection (over Mimic and OpenVPN). Lots of countries to connect to is a plus, but I have managed with fewer options.