The tight end position is diverse, making it hard to describe a prototypical player. You always like your tight ends to be between 6-foot-4 and 6-foot-7, but bulk and skill can vary depending on how they will be used.
The best case scenario is always a well-rounded player, a guy with the size and nasty streak to be a blocker, but also the speed and athleticism to challenge defenses in the passing game. Those players are hard to find, and that is why you will see some teams that like to run the ball employ bigger tight ends that look like an extra offensive lineman. They may not be able to add much as a receiver, but it works because their main value is as a blocker.
Another team may sacrifice the bulk to succeed as a blocker in favor of a more athletic tight end who can run well and act as an extra receiver. The type of tight end a team pursues depends on their offensive philosophy and scheme.