Well its a matter of opinion. Tifosi are popular because its Ferrari however the 'genius's' would say Murk are better. As long as you have Murk or Tifosi your safe, if your running on Tifosi and your happy with them, just stay however Murk are the better option. Personally I couldn't notice the difference from when I switched from Renault to Mercedes but I am 100% sure Murk are better. Also slightly off topic but Beep Fuel is faster than Seashells!
I presonally noticed a huge differance on the wear rate ont he Tifosi vs the Crowsward (spelling). I have been swapping motors every 2 races since switching to the Ferrair power plant.