Thank you for your request.
I can’t answer your question, it depends on the trips you’re going to make.
The GA Night travelcard is valid from 19.00 and the Half-Fare travelcard allows you to buy tickets at half price for a whole year. Both are attractive offers.
I recommend the two offers combined. Now it’s up to you to decide what’s best for your travel habits.
You will find all the information here and here.
I wish you a nice day.