There's no such thing as 'future proof'.
I agree with that. Plus, define "future"? Is it 1 year, 2 years, 5, 10, 20? What kind of projects are you interested in? And why would you tie yourself so badly to a specific vendor/FPGA model right from the start?
So I personally wouldn't recommend an expensive and too complex platform for a beginner. It doesn't make sense IMO and too many features/too complex FPGAs may distract the beginner more often than not instead of focusing on learning the basics.
You can find many boards at the $100-$150 price tag (or even less) that would be more than adequate for learning purposes.
Digilent boards are great.
And if you're more of a hardware person than a software one, have a scope and don't care for LED displays and gadgets, you may even learn with a breakout board of some kind for like $30, for instance a Lattice MachXO2 breakout board. No problem implementing a VGA controller on those, although they have pretty limited embedded RAM. A much "beefier" solution at a very reasonable cost could also be a Numato Saturn board. Spartan 6, 64MBytes onboard DDR RAM, FTDI chip... $140.
This is general suggestion. As I got it though, you'd like to buy from Element14 since you have some credit. They seem to have Lattice as well as some Digilent boards. Limited choice though. They also have the ARTY ARTIX-7 which would be great for a beginner.