There is a good article on both here http://www.hardwoodinstaller.com/hardwo ... es-oil.htm

Simply put, water based is a harder and better finish but requires more skill to apply.

Thanks for your opppion and I beleave i'am going to go with a water based finish, but will the floors scratch easier then they would if I used an oil finish?

No. Many people have the opinion that oil modified urethane (oil-based) is better/harder because it is an oil based finish. This is incorrect and these opinions are based on comparison's with oil and latex paints. In a surface, film forming finish, the carrier (either water or a solvent ) only acts as a vehicle to "carry" the solids, which are urethane in this instance. After the vehilce evaporates (offgases), only the solids remain and leaves behind the film of urethane (a type of plastic). What makes one finish better/harder than another is not the type of vehicle (carrier, oil based vs water-based ) but the quality of the components and types of solids used. A waterbased finish with mostly acrylic molecules will not be as hard as an oil based finish with all quality urethane molecules. A two component waterborne urethane finish that utilizes a crosslinking catalizer will most often be harder than a single component oil-based urethane. These are general rules of thumb as some two component waterbased urethanes will use more acrylics than urethane and others visa versa. Generally speaking, an all urethane finish will be harder (less scratch/wear prone) than a acrylic-urethane mixture. However, the acrylics provide excellant flow and level creating an attractive finish. It is always a trade off. IMO, the best surface film forming FLOOR finish today is Bona Traffic. Others come close and due to nano technology, the race is on to produce an even tougher finish.

Gary, it is more than your opinion. It is an undisputed fact. Traffic is, simply put, the strongest hardwood finish in the world. Not even moisture cure comes close.

I have heard some great things about Basic's line of products, but Traffic is in a class by itself.

While hardness is certainly important, the "Look" is also something that should be considered. Many of our customers that have had both finishes in the past are returning to oil based because they've found it to be "warmer" in look and tone.

Just something to consider.

A warmer look and tone can be achieved with a waterbased floor finish by using a neutral/natural stain prior to finishing and/or adding an amberizer to the finish.

I can honestly say that, having seen the use of Neutral/Natural stains prior to finishing, I don't find they match the depth of tone the oil finishes do.
As I've not seen the use of an amberizer in combination, this may well make the difference. Given how the products affect the wood and finish, their combination certainly have the best chance of duplicating the look.

One other route would be a oil based sealer followed by waterborne top coats I think it gives more depth than an oil stain alone.

I agree with the oil sealer first. It does look better. For a water finish, ive been using trek plus. I havnt had any problems with it and it is extremely hard. I just finished my house with it.

All I know is the contractor will be out this wed (11-02-05) and they are sanding 1000 sq feet and gonna use oil Based Polyurethane (3 coats) AND should be done in 3 days they said.