who is better, Ironfist or SIF?
If you're still trying to get Valkyrie, it's worth noting that if you have an Asgardian (AKA Sif) it will make Task 14 much easier, since you won't have to rely on Team Up missions to take your Asgardians into battle. Not a huge deal, just worth mentioning.
Modern armor Sif is better than Iron Fist. At this point, both of them are in a similar power tier of playable-but-not-amazing, but Iron Fist has an alt pending so he might be better once that arrives.
For me, Sif is better than Ironfist. Not only because She has an alternative Uniform but also since you can abuse her LV2 attack that causes tenderize which is a rare debuff that causes the target to take extra damage from slash attacks. Slash-based weapons / heroes who use slash attacks aren't that rare, so it's fairly easy to make your hits hit harder. Her stats are also better distributed that Ironfist's who for me, is a "Middleman" with no great stats except above-average envasion which isn't too useful with all the high accuracy heroes. While Sif has horrid envasion, she plays more defensively in terms of stats meaning she can last a bit longer. I like her skill set more than Ironfists as well.
Ironfist isn't bad, he is an average hero. His best move is probably his LV6 which works as a back-up healer. His LV1 is quite generic and does OK damage while his LV2 requires some luck or a specific setup to trigger deadly crits to do good damage.
His LV9 is considered one of the worst LV9 moves and even with the buff in making it a quick action. The biggest complaint is that the boost is quite small and doesn't make a big impact with one boost. Volcano players might find decent use for this move as he can become quite powerful after a few turns. I think there are quite a few problems with this: Most battles don't last much so you at most get to use it 3 times a battle before Ironfist is KO'ed. If you don't have a heroe that can protect him, don't expect him to last much unless you ISO him in health and defense. With some effects being able to remove beneficial status especially the Scroll Of Angolob that some players will get after season 3 ends boosting effects will become much weaker. Since Heart Of Shau-Lao is an already weak boost it makes it even weaker than it already is.
modern armour sif, hands down. use her lvl2 hit up to 3 times in a row g'teed hit and crit (not counting those few who have 20-25% 'dodge' talents) with accelerated damage due to her 'tenderise' debuff. generally kills any opposing player. on the other hand ironfists lvl2 attack which is supposed to be a monster- its what hes famous for afterall, generally does about the same as his lvl1 attack. in other words; stuff all. i think her lvl6 blade hone should be a quick action with a 2 round cool down. its not worth wasting a round doing no damage for it.
modern sif is up there in terms of first round scrapper damage (stroke of luck starts cooled down for claws black cat). with a quantum jumper, that second leaping slash deals a LOT of damage since you get the slashing bonus from tenderize in addition to the exploit tenderize bonus.
Sif is AWESOME. For real. In the Spec Op, she's cut Mystique so bad, that the beeotch died just out of pure bleeding, hands down to the Asgardian! Iron Fist is cheaper though, but that's the only advantage he has over Sif.
Sif's bruiser armor is amazing but if you seem to take large damage, then get Iron Fist.