Shield charge OR whirling blades? whats better

Depends on whether you're totin' a shield or two badass swords, my dude.

Edit: Okay but I guess I can give you a serious answer.

Given that SC scales based on both attack speed and move speed and seems to have a larger AoE (for things like Fortify and Endurance Charge on Melee Stun and stuff), it's at the top of my list. Also, lots of builds run shields, whereas a somewhat more limited subset carry daggers/claws/swords but not shields. There are a lot of them, yes, but lots and lots of, for example, spellcasters like shields too.

On the other hand, if you're using an off-set for movement, like a lot of lab farmers do, Leap Slam is really good if you can put all of your resources into making it fast. So not only do you have to use the usual combination of movement attack skill + faster attacks, you'll need other stuff makin' you super zippy too. The classic combo is Brightbeak in the main hand and Prismatic Eclipse with three green sockets in the off hand. But this is only if it's your weapon swap. Woe to the mapper that has to use this for their main weapon set. Having a DPS ceiling is misery.

Meanwhile Whirling Blades is super easy to use and doesn't require ANY building around, you just gotta have some blades to whirl.

Also, there are the spells that also do this, but they're kind of garbage and require a lot of messing with to make any good. Like needing both Faster Casting AND Reduced Duration, like Lightning Warp, to not just be strictly worse than a well-rolled Quicksilver Flask.

So my estimation is this:

Best movement skills at the top but also the strictest requirements to be used

Worst movement skills / loosest requirements at the bottom

Leap Slam
Shield Charge
Whirling Blades
Lightning Warp
Flame Dash

There's also the bow one but I don't do bows really so I have no idea if it's any good. But you gotta have a bow, so there's already that requirement that narrows its availability down a whole hell of a lot.

SC

Shield Charge is great when you're actually doing weapon damage. Just link Endurance Charge on Melee Stun and you get free charges, plus Fortify, of course.