P3RS, P6, Marantz TT or RP8

I'm not familiar with the Marantz 'tables, but you certainly can't go wrong with any of the Regas you mentioned at their respective price points. 

I toyed with all of the Rega turntables you're considering but - in the end - I went with a Michell Audio TecnoDec and T8 tonearm (the T8 is essentially a Rega RB880, with maybe a few tweaks by Michell).  The Michell inverted bearing design was really what sealed the deal for me - it's the same bearing used in the most expensive Michell models and is unique in its use of an Archimedean spiral milled into the spindle that helps to continuously circulate bearing oil.  It's certainly one of the quietest 'tables I've ever heard and I have to believe the bearing design is a big part of that. 

You can use a wide variety of arms with the 'table, including the usual suspects from Rega and Michell (whose arms are modified Regas), but Michell can also supply armboards for a wide variety of arms.

Just a suggestion if it's not something you've considered.

I was looking for a used technodec but they are almost non existent.

The upcoming Rega P6rs which includes their newest and top level MM cartridge the Nd9 looks intriguing and has great reviews. Coming to USA this summer.

Rega P6rs

Rega P6rs review

but that puts you in a totally different market. 

and will have the same only half the adjustments needed tonearm. They may be good tonearms but if it limits cartridge selection in the future not sure that's a good choice.