They both work. I was first taught to use the tape and used it for many years. When I heard about the paste I tried it and had fewer leaks. For probably a year I sore by the paste, never a leak. Then I had a leak with the paste. So now I use both (not on the same fitting).
For me the choice is based on conditions. I like the tape in wet conditions meaning the threads are wet. If the wind is blowing and there's loose dry dirt (welcome to Phoenix) I don't reach for the paste first as dirt can get into the paste and jam the thread.
You do want to be careful with the paste because it lubes the threads making it easier to over tighten which can lead to a cracked female in the years to come.
I follow a kind of process. Generally for 2" and less plastic pipe I start with the tape. If I have a leak, maybe 5% of the time, I remove the tape and try the paste. If I still have a leak, happened a few times, I remove the paste and use pipe dope (has to be right for the fitting's material). Pipe dope is heavier and more gummy than the teflon paste. If I still have a leak I remove the dope and check the threads for damage like I should have done at the very beginning. Maybe I can fix the threads, but generally it means replacing both the female and male but that's pretty rare.
If you really want to be smart you can use a temporary plug right after sealing a fitting and test the connection. If there's a leak it's easy to unscrew and try again. If you wait until the very end you may have to cut pipe, try again and add a slip coupling, which I never have handy of course. Or add a union which cost a fair bit.
Why not start with the pipe dope? If you don't have the wide gaps it fills it's no help and gets in the way of sealing normal tight gaps. Plus it's more messy than teflon paste. Very sticky. The teflon paste is more messy than the tape. So the tape is fastest if you don't have a leak.
If you're doing just a few fittings and you have no plumbing experience I think the teflon paste is best. It takes the least experience to get right. Use a clean brush and apply to both female and male threads. No need to go crazy with the amount. Tape takes a little getting use to. Not super difficult, but a bit of of learning. With the tape I see people generally put way too much on, no lay it flat, put it on in the wrong direction. And the info out there isn't very helpful on how many wraps to apply. I like 2, maybe 3 but some plumbers do 7-10 which I never understood.
Having said all that...for 1" and under I've been impressed by Shark Bite type connectors. Expensive but in some cases they're a big help.
