You don't comment anything about the weight of the equipment or the size, so I suppose it won't matter much to you...
I use an Air of 11.6 and I'm delighted, but seeing that you're looking for a 15-inch or so, a colleague bought one of these not long ago:
Samsung NP530U3C i5-3317U/6GB/500GB/13.3" NP530U3C-A08ES Portátil
And after removing the disgusting (pardon me, it's a personal taste) Windows 8 and putting Linux on it, it flies, literally flies.
The / directory on the 24gb SSD it has (more than enough for the system) and the /Home on the 500gb conventional disk it has. I was very surprised, it's light, small, fast and above all it has ETHERNET!! not like the air...
If you're looking for a 14-inch one, you have this model
Samsung NP530U4C i5-3317U/8GB/1TB/GT620/14" NP530U4C-S01ES Portátil
Which has a CD, 16gb in flash, and 1TB in hard drive.