Hello Seb

Well all three cars, ed30, gti, .:R32 all have great handling as standard! the .:R has all wheel drive so will probably feel more planted on track as standard even though weighing considerably more.
As far as modding goes theres only so much you can do to the .:R powerwise exhuast, intake, shrick cams etc, or if you wanted to spend quite afew £s then you could go down the HPA turbo route, 500HP plus is possible

The standard Gti, can easily and safely be remapped with the appropriate mods to 280ish HP give or take.
Where as the ED30 has a larger turbo (K04) with uprated injectors, larger inter cooler etc, with just a stage 1 remap alone you will see 280HP, and then dependent on budget high 350+HP is possible!
Either of the three cars are superb, and have a fantastic chassis with so much potential!!
If it were me buying again id go for the ED30, all round great car as standard, but so tunable! just check out Hurdys car in the mk5 build project section!