If you're building up a collection of Defenders, the best to focus on are:

Sentinel of the Skyways: Fortunately you already have him.

SI Namor: He's the Defenders' powerhouse, and he's still cheap enough to build a team around. If you could only have two Defenders I'd recommend these first two; they made the top 8 at a major conventin tournament by themselves. Namor is also keyword-friendly to multiple Defenders TA affiliations (Defenders, Invaders, and All-Winners Squad).

SI Dr Strange: He doesn't have the team ability, but with Defend on his first click he can lend out an 18 :d-shield: when required, and as a wildcard he can borrow another Defender's defence value when required, so it works just as well. Long range artillery and support all in one.

SN Valkyrie (EV): Both are helpful in different ways; if your force already has a decent number of 18 :d-shield: characters then the experienced gives you superior damage-dealing potential, whereas the veteran has the cheapest 18 :d-shield: by nearly fifty points.

ULT Hellcat (V): Fantastically cheap with a strong attack value and 4 damage when she uses Close Combat Expert. Super Senses on top of a borrowed defence value will frustrate attempts to take her out. I haven't had a chance to try her with Lunge yet, but you can bet that I will.

AV Gargoyle: He was on a lot of winning teams during the Coming of Galactus tournaments, mostly because he can push to Probability Control and has a seven-click dial with Regeneration to help extend it. He's fairly cheap and has some versatility as a secondary attacker or a support piece.

SV Silver Surfer (E): When you want to splash out on points, use this Surfer instead of Sentinel of the Skyways. He loses the 18 :d-shield:, but his first five clicks are all exceptionally dangerous and he has some Regeneration to help extend the ten-click dial. He's a little underpowered at 189 points, sadly.

IC Hulk (E): Sadly this is the only Hulk we have with the Defenders TA. He's not great, but with some high combat values down his dial he makes a great meatshield or Warbound partner. Only two clicks of Battle Fury makes him a better choice than the EV Hulk from Mutant Mayhem.

SN Kyle Richmond (LE): Very similar to the veteran Nighthawk, but I feel that the Limited Edition figure edges him out with early Close Combat Expert instead of Leadership. With Charge, Super Strength, and Willpower, Kyle Richmond can strike for four damage in one turn and then another four damage in the next. You could use the veteran if you have points to spend on something like Contingency Plan, but as either version of Nighthawk is likely to suffer a bit of damage, there's no guarantee you'll get your points worth there.

I've left out any Invaders, Guardians of the Galaxy, or Squadron Supreme members; while all three of those lineups are rpetty strong, they don't thematically mix with the actual Defenders. Pick them up and play them seperately rather than mixing them together.

Well i will definitely get my hands on some of those. i have the gargoyle, and can get the hulk pretty easily. yeah, once i get some of these figs i will definitely let you know how effective they are. and if you wanna trade any i am more than willing to trade whatever i have (mostly) for some of those guys.