Size: Think about the size of the work that you want to do and make sure that the press is large enough for want you want to do.
Heat Press Type: Swing-away, Draw and Clamshell heat presses are the three major types of presses. Each type will have certain advantages (remember, thinking about what you need and want), depending upon how the manufacturer constructs the press.
Digital time and temperature: Analog [using a dial] timers are often not quite as accurate as digital timers (and many only go up to sixty seconds) and analog temperatures are often read from a tiny gage that is often hard to judge correctly. In the real world, a totally digital press is not essential (i.e., it does not affect the ability of the press) it just makes you more efficient, with less to deal with.