What is a good RF transceiver to use when you first start competing?

There are a LOT of preferences from builders and, as such, there is no single right/wrong answer to this question. Below is a list of wireless communication methods you could start with, along with a brief description:
Flysky FS-i6X 10CH 2.4GHz AFHDS RC Transmitter w/ FS-iA6B Receiver: ($50 US) This is a good “starter” package which is affordable and relatively simple to use. It was recommended to me by several seasoned competitors at an event in 2019 for Antweight and Beetlweight bots.