Hi mate.
£1k budget
First and foremost if you want the best value for your money, do NOT buy new. At £1k you do not get good value in projector land. If you want a bright projector which will have placement issues, not the best black levels but great 3D, then go for the 2 projectors you listed above.
Ok now that out of the way, if you want best in class, filmic, awesome black levels, you have 2 different routes to go down.
1. <£500 Route - this is, get a £2000+ projector from 5 years ago which is premium, has amazing lens, amazing picture processing, amazing motion, amazing blacks and contrast BUT is 1080p.
Your options here are Sony HW40ES+, JVC X30+ and the Panasonic AE8000.
Sony = Awesome input lag, good all-rounder,
JVC = Best in class contrast/Blacks, dimmer
Panasonic = Some cool lens memory functions not found on any other projector, smaller form factor, brighter
2. <£1000 Route - this is Epson or JVC. 4K E shift, premium features like electrical zoom and lens shift.
Epson 9300 = 4K (not native but close), HDR - only limitation is its capped to 4K/30 so not 4K gaming, so you will have to do 1080p HDR gaming 60fps. standard price is <£1100
JVC X5000 = best in class blacks, beautiful, best contrast, just a better projector than the above but dimmer, 4K (not native), HDR, 4K/60, normally its available for £1250-£2500
The cons of the JVC are the lamps are VERY expensive so they will cost you.. and if someone has already clocked 2000 hours, a £1000 purchase is going to end up costing you £1500. JVC has crap customer support and warranty is not transferrable so that sucks too for a projector which can break easily. also no 3D emitter.. so you buy it seperately... so as I said.. it all adds up sneakily.
Epson pros over the JVC - this is a big one - every projector has 5 year warranty if bought in the UK. Just need serial numbers. bulbs are cheap AND the bulb also has 5 year warranty. The repairs are quick, seemless, easy. The Epson is also much brighter, its a light cannon so if you in a normal room which doesnt have black ceiling and walls, this PJ will come in use more. And its cheaper.
If you want to go new.. then just ask RS what they suggest. All have pros and cons and it comes down to more so placement and what lens shift they do or don't offer.
If you go down the £1000 route, download MADVR BETA version and enable dynamic tone mapping for HDR content and films and TV shows and play them locally off PC and let the PC decode and map the HDR content to the projecotrs (either in SDR or HDR colors.. u can pick.. the SDR will be brighter).
If you go down the Epson line to the 9200, 9100.. you lose 4K but most other things I stated stand. Similar to JVC.
also the BEST improvement to ur PJ experience will be an ALR screen. These are EXPENSIVE to buy new but good deals can come up for them. Best ones I found are draper react 3.0 screens.. these screens allow u to watch the projector with some light on in the room and fight sunlight really well.. especially with an epson.