Who had better voice Sinatra or Bennett?

Bit of a subjective question!

Sinatra himself referred to George Jones as 'second-best' in the world (sources are ambiguous about whether he said 'white' or 'male' along with that), reserving top spot not for himself, as many wrongly-assume, but for Tony Bennett.

I will leave it at that. There are lots of articles written on comparisons between the singers, lots of forums etc. I encourage you to read them if you are interested.

It is a tough call, and they were both brilliant.