To choose the best Gigabit switch, you should know how many ports you want in the first place. For SMBs, 24-port Gigabit switches and 48-port Gigabit switches are generally used.
Except for port numbers and types, other main hardware performances (forwarding rate, power supply, etc.), functionality (stacking, 802.1ad QinQ, etc.) and services are also important factors when choosing a Gigabit switch.