Hendershot actually has a really nice athletic score. He is average sized and has average long speed, but his 10 yard split shows good burst, and he crushed the agility drills. A 6.90 3-cone at 246 is sick.
Ferguson's numbers came in really similar but a tad slower. Average size, average speed, plus agility.
One thing I would like to mention is that the combine does an extremely poor job of measuring game strength, and TEs need it both in blocking and in bodying up defenders for catches. Witten, Gronk, Kelce... all three can or could move phenomenally well for 260 lb men, but they could also throw DBs around like Pop Warner kids after the catch.
If I had to put money down, I would say that Ferguson is stronger right now, but neither one is forklifting DEs out of the hole yet.