As assassins, they're both good in 1vs1, depending on the enemy. both can burst an adc/mage/assassin really fast (talon is quicker), but have no chance vs tanks
I prefer talon, but i cant deny fizz is better. He has more cc, awesome mobility and more damage on abilities (both can burst with 1 combo, but talon needs his full combo unless fed, while fizz only needs to hit his R and E). Talon is also countered by armor, while fizz can build both ap and ad (only ap works as an assassin tho).
IMPORTANT: Talon burst is quicker and hard to counter, because he blinks and you're dead, while fizz needs to use his Q or E to get close (non instant gap closers) and his ult needs some time to deal damage. With talon, the enemy adc is dead, with fizz, the carry can flash, the tanks can get ready to cc fizz, etc (he gives enough time to be countered). Fizz is also banned all the time, so i would buy talon, if i was you.