OK, I'd like to hear some options and opinions please.

Currently in the market for a new phone, tablet  for flying...  

I've considered CrystalSky. But add the power supply and the bracket and that's £550 plus. And that all it is, a display for DJI Drones, nothing else.  

A brand new Ipad starts from £319 and its a great tablet.  But im not sure how bright it is ?   

A Samsung Galaxy S8+ says its brighter than a Crystalsky. A nice phone how is it for comparability?  

I have a Note 8, which has one of the biggest and best screens available on a phone.  Note 9 is supposed to be even better, in specs at least.  After flying a new times though and reading a lot of threads here, I decided I wanted something a bit bigger for use with my MA, so I purchased a refurbished iPad Mini 4.  I'm not an Apple guy, but I'm really happy with it.  Got the 4g version so it has GPS and I can download maps, etc. without having to be near a Wifi point.

If you're happy with your current phone, consider an iPad mini.  You don't say what model you have, but it fits perfectly in the remote for the MA.  Anything except the 1st generation mini will work (app won't install on the gen 1), although the screen on the 4 is the nicest and supposedly has anti-glare properties.  There's plenty of refurbished ones on EBay.

I have been  using the iPad mini 4 since I got Th Mavic.

It is the 128Gb wi-fi only version and I have  dedicated it to the drone from day one. It is a perfect fit for the controller and I have had no problems with the screen not being bright enough. On occasion I have used a sunshield depending on time of day and location.
If you need GPS maps you can always piggyback a cell phone using it's wi-fi. I hardly do that . I cache the maps of the location I am flying and  it works for me.
Good luck making a decision on what ever you choose and happy flying.

I'n kinda looking at 3 atm..... ipan mini 4 128 meg wifi 399
ipad 128 meg wifi 409

Samsung galaxy note 8 phone  400-500   but a super bright screen. brighter than crystal sky...

but im old and also prefer a slightly larger screen old eyes and sausage fingers dont do small good ....

The most important issues that you have to consider are the cash memory of the device and the brightness of the screen. The first (cash memory) should be suitable to deal with a heavy app like Dji go 4, the second (brightness) to see better.

The best device is the one with 4 GB cash memory (a must have).

The best screen brightness devices are the phones not the tablets.