Tower system

I assume you mean full tower case? Like a knee high a case with tons of room, but empty. That depends on you, toss some spec to newegg and drill down based on number of drives ect. Unfortunately full tower cases are out of style and even a simple big box can be quite expensive. You might try local second hand computer shops, where full towers cases are cheap and abundant, and just gut any extra out. I saved $300 doing that.