I have driven both cars, the 8th gen look better, more masculine, but the 7th gen are the better all around car if you ask me. Both are NOT sports cars, and they shouldn't be, but they are fantastic for the segment they are in. I own an 06 G35 and have had these cars almost side by side. The 7th gen is fantastic ALL AROUND, the VTEC system in that car spreads the power ALL across the RPM range, it is really impressive, the 08+ have a discrete VTEC kick, like what I used to experience in the 2003 CL-S, good but not "great".
More than that though, the 7th gen is far lighter, I used to think it was negligible but no, it is significantly lighter and you feel it all the time. More than that, the gearing for the 7th gen is both great for acceleration AND highway cruising. The performance between both cars is negligible but the interior is nicer in the 7th Gen (opinion though) and it gets much better fuel economy while being pretty damn quick.
I loved the 6MT in both Accords, but, I am going with AT's for my daily driver these days. Regarding this, the 7th gen DOES NOT have VCM technology and the related oil consumption problems, also, it does not have the complex motor mounts that are supposed to compensate for the additional vibrations felt when VCM starts disabling cylinders (3 and 4 cylinder operation). The 7th gen is just the engine and a regular torque converter based auto transmission (though admittedly the 03-05's were known to have transmission issues, just like the TL's of the same vintage).
The J30A4/A5 is more "power dense", it makes more power per litre than the J35's, and the VTEC system is designed for performance NOT economy, though I think on the 08 6MT it is also "performance oriented", so I suppose that's moot.
All that said, I will be buying an 06-07 Accord V6 Coupe to replace my 06 G35 Coupe, so that should also say something, other than "I'm crazy". I had all 3 cars to choose and I keep coming back to that damn 7th Gen Accord...if only it didn't look like it was styled after a soap bar
Though, I guess you can't have it all...well, unless you can afford an S5