The part i like about entry #1 is the second part of the logo or the "1". I would lik eot see the text change slightly. Possibly a combo of all three?
Some variations might include
Entry one with the text slightly larger with the same "d". Keep the "1"
Entry 1 with the small fonts like entry 3 - Keep the "1"
How about entry 1 with the blue (stethoscope made up of the letter "c" and the Letter "o", Basically the "c" is replacing the original "D" as the ear ends
Just some ideas