First turntable advice

Project would sound better IF you put a better cart like a Nagoka, Denon etc. Rega probaly would if you did the same. Its your money.
IMO Rega carts are dogs.

I'd vote for used Technics 1200 MK2 or you can purchase new with mods from kabusa.com. It's undisputed built quality, ease of set-up, fully adjustable. Moreover it will never drop the price, because it's legendary.

Is there a Rega P6? There's an RP6 and a P5. The P5 is a very good TT for an analogue novice. But you would be buying that unit used, so it's a risky move, unless you know the history of the unit or if it's a dealer demo.

One piece of advice from my experience, you should start off with a MM cartridge, then the TT would really be "set it and forget it." And I would not recommend a Rega cart; very high output and hard to match with a basic phono stage (phono preamp). There are many other carts that perform better and are less expensive.

Night and day Narunner2, night and day. There is no fair comparison between the two. Instead, you may want to compare Rega RP1 with the Carbon Debut.

Personally, I prefer Rega but that's my opinion and not yours.

Either one will pair well with your equipment provided your set-up is spot on.

I second Schubert's advice, visit a local dealer, trust your ears, and buy a new one.

Happy listening!