What about M135i? Hard to overlook them if you are talking 25k spend
Not concidered the BM (never been in a M135i so can't comment really), yes they are as fugly as my scrotom but by all accounts a great engine and all that RWD sideways fun.
I think it depends what you're after exactly. If you want something to compete with the eddy in terms of being special and rare then the MK6 R in good condition and a desirable colour red/ white is probably the one of the three that's going to come closest. The RS3 is too boring to look at and the 7R is well.... Just another 7R
The RS3 has the most potential as a driving machine as the 5pot is a peach of an engine and you could make a real monster with a few quid.
The 7R is probably the best all round though, great value, very quick without spending much and the newest of the three and personally I love the MK7 interior. Thing is with some springs and some different wheels you can still make the 7R stand out more from the others and people will know you're an enthusiast and not just an insurance rep 
Good luck 
I agree with all of the above Dan.
If I can get the exact Mk6 I want for a good price I still will, I just don't think they are worth £20k+
As for the Mk7, some nice wheels, lairy coloured BBK and some lows (plus the obligatory power mods) and it won't look like a rep wagon for long.
The RS is now towards the back of my list unless a fully loaded minter with wingbacks and low miles turns up for a steal.
335i?
Ok ish. A friend of mine has a M3.....that's a weapon but my friend is also a nob so that's a no.
