Unless the weather is below VFR conditions (like last weekend, as suggested above) I would guess that the busiest periods, in general, are roughly 11-15.
If you have budget to buy one hour only, I would probably go for 13.30 to 14.30.
But... I would look at the METARs first to determine when the weather was below VFR conditions. This site allows you to view historical METARs:
Formulario para peticion de mensajes aeronauticos