If so, which one? Would you recommend it?

do you find yourself using public wifi often? If not, then you don't need it.

What if I visit a lot of questionable websites?

Mullvad

I've used Private Internet Access for years.  It's pretty affordable and easy to use.  I'm sure most of the top ones are all pretty similar in features and performance.  A sub offers use on up to 10 devices, including mobile.

A couple of good features is I have an icon right in my tray, and can block all internet access if the program is disabled.  Uses its own DNS, and offers "multi hop" that routes you through 2 of its servers.

It DOES cause issues with a few sites, mostly financial sites, that don't like IPs with a lot of traffic, for obvious reasons.

I use Nord.