I too ride my commute in "bat out of hell" mode like a roadie. Having a load in the panniers does not necessarily mean losing speed or zippiness. Except in stiff headwinds, and then it just makes you stronger for other rides.

I've found nirvana with Tubus racks. What I always thought was pannier sway in the back, turned out of be rack sway instead. I never knew until I switched to a Tubus. The extra rigidity is noticeable.

Pannier choice is largely a matter of personal preference. Some folks like big empty space, others prefer many smaller compartments. Let your backpack usage be your guide.

I don't tote many folders or papers, so the big empty space kind of bag is my preference. I like my pair of Ortleib Bike Packer Plus panniers. They're designed as front panniers for touring. I mount them on the back and find their smaller size to be perfect for commuting.

My guess is that you might be well served by one of the office commuter panniers. (like the Ortlieb Office Bag or Arkel Breifcase).

Then again as a longtime backpack user, you may prefer one of the backpack panniers. Arkel makes three different backpack panniers. There are others around too.

Or you may end up with a mismatched set--one with compartments to keep papers straight, and another with big empty space to hold food, clothes or shoes and stuff.