The base/included antenna with any GO Kit works very well. However, if you want to push the limits of what your kit can do, you may want to consider an additional antenna option. These antennas are made by MakerNova.
 
Compatible with any GO Kit (SMA connector)
10 dBi of gain and an optimized 40cm length
Professionally tuned for the 907-915 MHz US/AU LoRa bands with an excellent SWR of ≤ 1.5 for peak transmission efficiency
Durable and flexible construction ensures reliable performance in outdoor and mobile applications