Re. DC5 v 200 v R26:
The DC5 is a cracking car, plus there's the rarity factor and they're awesome straight out of the box. They're not cheap to modify though and suspension setup is difficult once you do. They're not as raw as you'd think either, if you're after a hardcore experience you would be better with a DC2. Then it's an older car though.
Without being overly biased, the 200 is probably one of the last old skool basic hot hatches. NA, fairly light, fairly low power but with a massively talented chassis, even with the simple hardware. There's a reason I've kept mine from new rather than gone the DC5 route. The mods I've done recently have made it even better too and they're cheap enough to run as well as responding well to mods. I like the 200. Good car.
R26's are also great, but feeling their age nowadays, if you're bothered about interior etc. The 250 onwards are weapons with a few mods, really awesome cars and if I was about that boost life, I'd have probably bought one over the 200.
All that said, Z4M's are lovely, but they're going north in price very quickly. ISF's are cool but I've heard the auto box and intrusive ESP kills the fun a little. They'd be a great daily though... maybe get both?