Both have their advantages and disadvantages, and there are a lot of posts floating around the forum comparing them. Personally I use Zigbee2mqtt because I have a device that was better supported in it. Zigbee2mqtt supports more devices, while ZHA generally supports more zigbee controller sticks. ZHA is built into home assistant, so no separate addon, but some like the separation as restarting Home Assistant with zigbee2mqtt doesn’t restart the zigbee network. This guy did a pretty good video comparing them
