If you're going for looks, I'd say GSR...If you like civics, go the other way...or do the best of both worlds and swap a GSR/hype R INTO a civic...really personal preference--on looks alone, I like the Integra...for a breakfast blend of looks and not much more power, do up the swap...

civic has a B16 ( 1.6 litres )
GSR has a B18 (1.8 litres )

Both about 180 hp, the GSR will get you 10-12 ft/lbs more torque...

main difference in the engines is the rpm range...civic ( B16 ) rev's higher, GSR ( B18 )has more low end...

In reference to which is 'faster', it's more about the driver's ability, rather than the car's.
Now the GSR will be more 'luxurious' ( I use this term loosely, they're both hondas ) than the civic, i.e. a little more insulation, so not as much road noise, and 'sport inspired' suspension; but, again, not much difference since they're almost the same car, just the bodies are different...


I just realized that I didn't help in anyway...if anything, I just made your decision harder...

Although I would say a GSR swapped civic has more potential to be a super sleeper...people out of the scene expect Integras to be fast because they cost more