First Things First

[fdheld34]

I hear good things about a product from Home Depot. If I remember its an epoxy and has a color fleck for the top. A buddy used it (indoors) and loved the stuff. Oil and grease washes off it.

that would be the rustoleum 2 part epoxy shield...I have used it on driveways, patios and with / without flakes..no callbacks. I also used it on detatched garage and the Bobcat can turn around without excessive marks etc.

I have used H&C xylene based stain.. with subpar results...driveway... tire marks etc etc...ok for patios etc.
Epoxyshield rolls on ok...I have had some roller marks and slight variation of color on some jobs ...if you used the flakes that will mask it.
On my bigger jobs I use Ultracrete/ hydrostain (Color Wheel)and airless with excellent results plus its easier to clean up and move on.
check concrete for moisture too..meter or place item on crete if come back and pattern is still there..wait more time etc. After pour wait a month prior to stain/paint application...obviously different in other cases like stamped concrete overlay etc.

For your outbuilding I would go with Epoxy shield..just my experience and 2cents worth
-Fred