Third after, figuring the max all loaded up weight your truck can take and your budget, is a list in order of importance, IMHO.
The "Must's", the "Would be Nice's" and the "Don't Need/Want's"
Some things are determined for you by weight capacity and budget.
And measure your truck bed and compare with the TC bottom that will be in there. If the TC don't fit, you must leave it! ( my 98 GMC's bed tapers narrower in the back giving just an inch on either side.....:E )
TC's seem to very much involve compromising the fantasy for reality.