Second hand record turntable - Which one?

There are several early Technics direct drives that are easily restored fairly cheap that would satisfy.

I think Rega has a better arm.

The way I think of it, there are two reasons to buy a used TT. One is to save money over the cost of a new sample of the TT you seek, and the other is because the TT you most want to own is no longer in production. The TTs you list are inexpensive, but you don't say how much you would be willing to spend on a new TT. If $350 or less does represent your "budget", then I would recommend you purchase something used, because there is not much to be found in the way of new TTs that would exceed or even equal the ones you list in performance. I say this although I am not myself a big fan of either Rega or Pro-ject. If you buy used, best to buy from a dealer or some other seller who is willing to guarantee the working condition of the TT. That warranty should be a major determinant.

Reva planar 3 it’s only 2 yrs old.

Both Rega and Pro-ject make decent starter level turntables, which is what you are looking at.  Since they are used the condition of the parts is going to make all the difference in the world.  Specifically you need to have someone who is qualified look at the diamond tips of each stylus under a microscope to see how much wear they have undergone.  You also need to have the belt of each examined and preferably replaced.  The motors should be listened to for noise.  The bearings at both the tonearm pivots and the turntable spindle should be first lubed and then carefully listened to for noise.  All of this is easily accomplished by someone who knows what they are doing and has the equipment to accomplished the tasks.  If these simple tasks can't be performed on the two TTs, my advice is to take a pass.  Assuming they both are evaluated as per above and are found to be OK, then you should play a record or two on each one preferably on the same system.  Do you like the sound of one better, if so that is the one to buy.  If they both sound similar, which is easier for you to handle?  Pick on the basis of ergonomics.  Finally, if all else fails, which one pleases you more visually?  The most important thing to remember is to have fun with this process.  Playing records is supposed to be fun.