What type of receivers do you have/use?
Do you want to deal with flashing (programming) your RXes and TXes "often"? (ELRS is in active development and is getting new features regularly)
also... if you have no idea what I just said, you probably want the 4-in-1 TX module, not the ELRS module (unless you don't have any TX/RX stuff at all and want to go straight into ELRS)