I prefer the "s" iPhones because of the CPU and GPU upgrades they typically receive.
The iPhone 4S (A5) to 5 (A6) was a huge jump in performance. Even today, the 5 doesn't feel inadequate for any tasks. It's probably more hampered by lack of RAM than processing speed as it constantly reloads pages and apps.
Best of both worlds (design and speed) with the non-S cycle.