This is my opinion:
Resist Physical Damage
Good auto that gives you res agains smashing/lethal, 3-slot with res enhancements and you get a good res against the biggest damage-type in the game. Drains no end.
Temporary Invulnerability
see above. Only diff is that it's a toggle.
Dull Pain
Good "self heal", gives you 70% more HP and heals you 70% (if I remember numbers correctly..) Many peopla use it proactive before a big fight to get more HP.
Resist Elements
Res against fire/cold and toxic (?), Auto just like the first. I've never picked it because due to the small amount of enemies that deals this type of damage, get another power instead of this.
Unyielding
The best power in the invul powerset IMO, Res against knockback, mez and such.. Never turn it off and slot for res and end red.. 
Gives res against all except psy-powers.
Resist Energies
See "Resist Elements", the same except res against energy/negative. I've never picked it.
Invincibility
Gives +DEF and +ACC for each enemy in melee range (up to 10 enemies), I slot it with tohit-buffs and end red.
Tough Hide
Basically a +DEF auto.. My build is heavy on Res and low on Def so I've never picked it.
Unstoppable
Fantastic power if you got Herostats to time it, When it wears off you have almost no end or HP. IMO a must for a invul-scrapper
That's my invul build and my opinions, I'm not sure of the numbers or the effects on some of the powers since I'm at work and cannot run the game to check..
Since the i7 respec is coming up I would like to know whether there is any powers in the invun set/claw set which are not worth having.
I have seen some scrappers and tankers who have skipped out some of the autos such as the energy res one and the element res one.