For my PITA hybrid defender, I went with a human ensnaring Swordmage|Warden. He's the stickiest defender I've seen in play. I can keep my aegis on one enemy, mark another adjacent enemy for free, and I have powers that let me add a third mark for a turn if needed. We hit level 6 recently.
For "sticky" powers I have Booming Blade (damage if they move away) and Weight of Earth (slows), along with Form of Winter's Herald (squares within 2 of me in all directions are difficult terrain for my enemies), Theft of Alacrity (save ends immobilize followed by save ends slow), and Treacherous Ice (enemies can't shift out of squares next to me).
For feats I've got Sudden Roots (my opportunity attacks inflict slow), Grasping Ensnarement (target of my aegis is slowed when teleported), Impaling Thrust (turn a crit into a normal hit to immobilize), and I don't remember the others. I spent Hybrid Talent on Swordmage Warding to keep my AC up without heavy armour.
On the utility front I've got Dimensional Warp and Breath of Chaos to get out of awkward situations. For items I went with an Aegis Blade (for when you absolutely, positively have to mark every single mother****er in the room) and Amulet of Life (encounter, spend two healing surges when you could spend one) since he takes bucketloads of damage on account of having the worst bad guys locked down a lot of the time.
This build doesn't punish enemies for respecting my marks, because I
want them to respect my marks. Often I force them to respect my marks by preventing them from moving away.
