How do I make defense based characters better?

I have a character with every powerset (except emp and pain dom--deleted those after years of them sitting). I find that I struggle to make my defense based characters as formidable as my resistance based characters (I am talking broadly, but this impacts my tanks the most).

For resistance based characters I can IO-up and get my defense incredibly high so that I am high on +res and +def. On defense characters, it seems I can easily meet and exceed the softcap, but have little +res (usually just something like adding [tough]). When I play these characters, they feel a lot squishier than the others. For example, for some teams my ice tanker rocks it, but for others I feel sub-par.

Anyone have suggestions to up the survivability for defense? Am I missing great IOs that add +res? Do I work toward massive +regen? Help?

Since the devs decided when creating IOs that everyone should be able to have super reflexes but no one should be able to have comparable damage resistance, your only option is HP/Regen.

My new build for my claws/sr brute will have him sitting at 2142 HP regenerating at 32 HP/sec. When he was a scrapper he had around 1850 HP and 27HP/sec regen.

Yes, it's unfair, but there it is. My next big bad will probably be an inv/fire tank.

There are a couple of things you can do. Generally, on defense tanks you want to build toward some alternative form of mitigation other than being indestructible. What you can do is give your tank soft control powers that are meant to slow down incoming damage. You can take the healing pool and six-slot aid self to heal the few attacks that get through.

For build purposes, you'll want to go with max HP, but if you have a control power somewhere you can also build for recharge.

That helps guys, thanks.

What about the "Presence" pool...is that helpful at all for mitigation?

Just to re-emphasize what Bill said, building for +hp and +regen can be really nice on defense sets without a heal (SR and Arachnos Widows, Fortunatas, and Banes) and to a lesser extent but still very useful for defense sets with a heal (ice armor, crabs, energy aura)