Yeah, yeah, put down the pitchforks and torches. Let me explain:
On flat ground, the 279e is undoubtedly stronger. Its lack of a lower plate and great upper plate makes it a beast. But that's really about it.
When both are hulldown, the 260 is way harder to penetrate, due to its (almost) complete lack of a cupola and its godlike 350mm frontal turret armor. The 279e has two cupolas which are pretty easy to hit and its turret is a bit thinner (although still 330mm minimum).
Next up – mobility. The 260's ridiculous hp/t ratio and high top speed, which rival the AMX 50B, allow it to take annoying positions very early in the game and be practically impossible to dig out. The 279e's 40km/h are by no means terrible, but they forbid the tank from taking aggressive positions.
Side armor. The 260 has the classic 'black hole' bar on its side, that can seemingly bounce anything. On the other hand, if you have the flat side of a 279e, you are almost guaranteed to penetrate.
Gun. While the 260 has marginally lower DPM, it has much greater shell velocity on its standard rounds (1259 vs 940), and it's aimtime, accuracy and dispersion values are all a touch better than the 279e's. I find that when I play against a 279e in close range, they will derp every 1/5 shots, while a 260 will only derp 1/10. At long ranges, the 260 is a much better sniper.
These are just my thoughts. I would love to hear yours. Which tank do you find more annoying to play against?