As you can see the coil helped. What else can we do?
If you followed this you should see the gain effects the roll off frequency and the input Z effects the roll off frequency. To get higher gain at high frequencies we need less capacitance. Placing a coil in the circuit can help with this. Using a lower Z will also improve the high frequency response.
Remember the capacitance will be there. You may find a better transistor for high frequencies. Look at the Ft.
A lower Z circuit will have better frequency response. Some RF designers use 50 Ohms for their I/O for this reason. The low Z circuit will have a higher current draw. For this reason a 5 volt amp may have lower power consumption than a 12 volt amp and produce the same gain. You can use this calculator to see the cut off frequency for different R C values.