Hi Gren
Nice to hear from you again.
A VPN will not noticeably slow down your broadband especially with the download you have. I have half that speed and don't really see much difference.
With a good VPN, it will offer choices, eg, to use the fastest connection; it will offer "favourites" based on your real location; and it will, or should have, a fairly global reach.
Choosing a VPN - well, you can Google "best VPNs" for example. From a general standpoint, I would say:
Avoid free VPNs - how do they make their money if not compromising on something.....
As regards pay-for VPNs, apart from Googling the "best", you might want to consider where they are based. For example, would the government of that country have the power to force the VPN to disclose your traffic and sites? Does the VPN "guarantee" not to track you or store info about you? Things like that. Check to make sure they a "kill" key which immediately closes the connection if there's any threat or suchlike.
Also, cost - an annual sub is cheaper than a monthly one.
You might want to think which country you would appear to be located when using the VPN and how many options are there for/in that country.
As to whether "it's worth it"; that depends on where you live, what your site preferences are, how concerned you are about security and so on.
I use ExpressVPN mostly when I need to. I used to use Private Internet Access (PIA) which is/was fine too. As others post to this thread, you will get myriad recommendations, I'm sure.
That's a start.
Ian