There's a Denon X4000 also, for £395.The Marantz, I don't believe, does Atmos - so at some point you'll want to upgrade from that - even if you don't plan on Atmos right now.
The other two are decent candidates - though I'm not familiar with the Pioneer.
I'm not directly familiar with the Denon either, but it's the closest thing to any of my Marantz gear that I've used in the past.
No idea, whether the prices are reasonable though - do you have an AV dealer close by? They often have stuff taken in as part-ex that might suit.
I'm not in a great spot in terms of AV dealers. They don't call this the forgotten country for nothing. I'd say my closest specialist is Coleraine, about 40 miles away. There was a home cinema specialist there, might give them a call in the morning.