Also alliteration's aidful art on Hebrews 4:14-5:10

If the alliteration here was not enough for you (a superior priest, a sympathetic priest, a sufficient priest), you might like the following from Nigel Beynon's sermon:

(1)   Jesus is a perfect high priest because he is perfect in sympathy (4v15)

(2)   Jesus is a perfect high priest because he is perfect in selection (5v4)

(3)   Jesus is a perfect high priest because he is perfect in sacrifice (5vv7-10)

There are no doubt a number of other "s"es one could think about: Jesus' suffering (v8), submission (v7) supplication (v7) sinlessness (v15) and Jesus as the source of salvation (v9) he has won. Maybe Jesus' sensitivity. Jesus' sonship. Perhaps it gets toooooo silly to talk of Jesus sitting in heaven or his heavenly session. The whole sermon could be cast as Jesus' similarity to the Old Testament High Priest and Jesus' superiority over the Old Testament high priest. You could always stick in a supreme. Jesus is a perfectly suitable great high priest. Stick with Jesus wouldn't make a bad application.   

Or from John Samuel's sermon:

(1)   Jesus is a heavenly high priest – one with God

(2)   Jesus is a human high priest – one with us