3 is the best.
3 and 2 generate the same (or nearly the same) bytecode, but 3 is easier to type and is shorter, so 3 is better than 2.
If trace is not enabled, 1 must perform string concatenation (“Time taken to store ” + count + ….) which is somewhat expensive, while 2 does the string concatenation only if trace is enabled, which is why 3 is better than 1.