What is the best cut of beef to serve to someone as a steak?

flat iron got the best meat flavor.

only 10 minutes left on here. 

flat iron is best

everyone has a different opinion on what is best, all depends on what you like to eat, tenderloin ( filet mignon is most tender, little dry but great ) t'bone /porterhouse are the same except for the size on the tenderloin on it's side of T/ bone.. both very good , porterhouse is somewhat larger because of the tenderloin.. if you take bone out them you get a new york strip with out the tenderloin, rib steaks are good l take bone out you get the boneless rib eye,, take your pick and see which one fits your taste buds best. 

Tenderloin for sure.

Those talking "Tomahawk" are full of ****!!!!! And NOT realistic.

They either did a quick Google search, or dumb enough to buy into expensive cuts cause they thought they were cool for knowing.

Not to mention, answering a Yahoo Question with a $500 answer, are they ******* stupid, or just need a bit of recognition towards their lonely stale lives?

Tenderloin is available all over, more pricey, but worth it.

Rib eye all the way, in my opinion.

I think a ribeye is far better than a T-bone. A bacon wrapped filet is also better than a T-bone.

Probably The best is the rib eye or Tomahawk. But both are rather expensive. Failing that, a good NY Strip would be fine. A T Bone is part sirloin, part filet. Don't much like the filet, tender, yes. But not very tasty. 

It's the Tomahawk Steak.

Sirloin or Tenderloin is good for Steaks.

My favorite is the filet mignon.  But it's very soft and some people don't like the texture.  If you don't like filet mignon, then the best cut is chateaubriand.  (IMO of course.  YMMV.)