I like the Marantz- the star in that particular package is the cartridge. Having said that I’m not sure I would buy it used not knowing if the cartridge was set up properly and taken care of properly. It depends on how much confidence you have in your own setup/ tweaking abilities to address any potential issues. I still like the Marantz package and think it is worth $1800 new with the cartridge checked and set up properly by a reputable dealer (Upscale Audio offers this service for free).
As far as the Rega goes, are you sure it comes with the Exact 2– for the price you noted it is usually packaged with Elys 2. The P3 is a nice table with a nice arm and definitely one to consider at your price point— I personally do not like the fact that you have to take the platter off to play 45s… not a deal breaker but a small quibble.
The real sleeper in this price range is the Consonance Wax Engine. It is associated with Well Tempered Labs and has inherited the Well Tempered bearing and drive system. It is often paired with either the Well Tempered TLC (made by Nagaoka) cartridge or the Charisma ECO. Not a ton of press on this table but it may be worth looking into— looks like Don Better Audio carries it.