More important even then what they are made of, blades for hardwood have to kept sharp. Dull blades are of course dangerous but with hardwood they can also lead quickly to overheating. Overheating the structure of a blade can cause it to warp and in the case of tipped blades, even cause the weld joints to fail.
You probably want carbide tipped/coated blades at the very least if you can afford and justify the cost. Diamond blades will return their investment if you have lots of cuts to make.
Running the motors for saws used to cut hardwood at a constant speed will also assure good blade cutting performance. Make sure your saw motors are suited to cutting hardwood.
Engineered hardwood floor are mostly plywood, and fairly easy to cut. Full 3/4 hardwood floors such as oak can be very hard. As suggested above, SHARP carbide tipped blades are best, and not too fine tooth, 10-20 teeth is fine. If cutting an installed floor, you will run into nails which are specially hardened and are hard on any saw blade.
For cutting flooring for installation, a fine tooth(40 + teeth) crosscut blade in a miter saw works well.