2 part industrial epoxy. But only after a calcium chloride test to determine how much moisture is wicking up through the slab. Too much moisture will lift any coating, and cause efflorescence. Not to mention creating a humidity issue for your home. Was amoisture barrier used under your slab?

We have a farm shop with office. In the actual shop itself we sealed the gray concrete with a product called Kure N Seal (purchased at a concrete products place). Really easy to do. Just clean the floor, apply the product while still damp and repeat a short while later. The more coats given the more durable the finish and the higher the sheen. We do have oil spots from where the guys work on equipment, but I don't think you would have that problem. The Kure N Seal come in both a solvent base (very stinky) and a water base. I applied it with an 18" roller. We used a large floor scrubber to clean it and it looks pretty nice when all cleaned up. I used a microfiber mop (like for basketball courts) to sweep it up. I don't think it gets slick.

We actually used a concrete stain on our office floor; however I would only do that again if a light color was used. We hired someone to do that and they used different products. Ours is too dark and shows every footprint. Plus where the chairs slide it scratches the finish. Wish we'd used the same product from our shop in our office area.

Does the 2 part industrial epoxy that hollysprings mentioned come in a clear formula? I've used the 2 part epoxy products for my garage, but I wouldn't want it in a basement.

We recently had the colored epoxy professionally applied to a new concrete garage floor and an on an old concrete section of the basement. It's textured for better traction. A different section of the basement was already dyed, and we used clear on it. I love the industrial look of the clear, and it's so thick and tough. It was pretty costly. The guys had to do a lot of grinding on both the new and old surfaces, and they had to come back a second time.

On the (outdoor) front porch and the (indoor-ish) screen porch my husband used H&C Concrete Sealer Wet Look. It is water based, and he says it was easy to apply. It does not take a long time to dry. He thinks it looks better with a greater buildup of coats. I suppose that's because it's pretty thin, and the texture of the concrete does come through. It does look nice, but it does not provide a smooth, easy-to wash finish like epoxy. (We actually had grain added to our apoxy to make for better traction.) I haven't spilled anything major on the screen porch, so I can't address whether it blocks household stains. The front porch is uncovered, and the coats he applied in fall, 2012 are still holding up well in our Midwest climate.

We have put it on both colored and undyed concrete, and it looks a little bit shinier on the undyed floor, probably because it is lighter/

If you have any specific questions, let me know and I'll ask him.

I'm not sure on that moisture barrier but I can stalk some of the new homes and see what they do. I know there is a black substance used on the outside walls and then gravel under the concrete floor but that's all I know.

These answers will give me much to google!

We plan to finish the basement in 2 halves/chunks but the floor has to be done all at once.