Looking for alternative to my Galaxy S7 Edge, iPad or Andriod tablet that will fit
into the Spark RC. Suggestions please.

i use the mavmount to mount my table to the controller.

I love the mavmount, but it's a bit pricey for what it is.  Even though the aluminum is sexy as hell. There are cheaper alternatives.  As per the original post, I find the ipad mini 4 to work fantastically between my Spark and my Mavic.  It does fit in the controller with some manipulation.  

you can get a tablet mount .. I see dji sells them now.  or go for the more expensive MAVMOUNT

It seems that all above are a little off topic. I would recommend to consider the iPad.

I do like the mavmount, thanks for the recommendations.

I started out with a Samsung tablet, it just couldn't keep up. I switched to an iPad Mini 4 and it works great. And I'm not a fan of Apple.

Yeah iPad Mini 4 is your best option at present.  
I am currently waiting for an iPhone 6S+ to arrive as I fancy biggish, but not tablet for the small Spark footprint.  It will hopefully save me having a phone and a tablet for my drones, can just use the iPhone.

I'd have to agree with the other comments in here, the iPad MIni 4 is best. Way prefer using my iPad Mini 4 to my Samsung S8. The Mini 4 has some anti glare coating on the screen and I find the brightness pretty decent. If there glare is ever too bad i just have my back to the sun if I don't have a sun shade with me. There's some good suggestions for tabletshere if you're interested.