If it's a car to use daily, then get the Mk6. It's a much nicer place to sit in.
If it's a play thing for sunny days, shows, that you'll keep for ever, then I'd go for the Ed30, having negotiated a more realistic price.
But if the car's to be a keeper, in 10 years time, the ED30 will be worth more money than the newer Mk6.
+1. Having owned both at the same time and driving them back to back day to day the MK6 is more refined and does everthing brilliantly so as a daily car it is a slightly better car. However the ED30 is more focused, slightly faster and more fun to drive, just as practical but gives you a bigger smile. Having done European Tours in both they are both fantastic Grand Tourers and just as capable as one another.
There is no getting round it one is 5 years old and the other 2, still with a warranty, if they were the same price I would get the MK6 assuming this is good value. Depends on how much you want to pay because there should be approx £7-9k price difference depending upon spec and condition.
More focused? How? The ED30 is just a MK5 with a bigger turbo.
The MK6 GTI is faster round a track than an ED30, but it can't be modded as much as the ED30 that's for sure.
It's the same with the MK6 GTI and the ED35, same car apart from engine, I read people saying similar things about the ED35 being more focused that a MK6 GTI, again I say how? Interestingly it's very tight between the GTI and the ED35 round Hokenheim Short -
ED35 1:19.00
GTI 1:19.80
Back on subject, if you're talking same money then you're either being ripped off on the ED30 or the MK6 GTI is a steal or stolen

Jim