hhmmm empty tank syndrome. That is a nice size tank, you could do a lot with it.
What kind of expense are you looking to put into a pet? how much do you want to spend monthly on it's care and feeding? Do you want to get something that needs a uv light and uv bulbs? Do you (or your parents) have a problem with feeding rodents or bugs? Or keeping bugs in your home?
Do you want a pet you can handle a lot?
Do you want something with plants in it or a more desert setup.
Do you want something that has to have a water area in their tank? Or high humidity?
I think it would probably be best to make a list of things that you and your parents are willing (and able) to deal with and then check out all the care sheets you can find to see what is best for you.
I finally got it all together but I forgot where I put it.