Tough choice between Torres and Fowler. Owen was brilliant, but not at the same level as Fowler. Torres has an amazing strike rate and can rip apart any defense on his day, but Fowler was simply more clinical from any angle. Torres needs those "on" days; if you look at his career with us he goes a few games without a goal and then gets brace after brace before going quiet again (and then inevitably gets injured playing for Spain). Fowler just seemed to score at will, though in all honesty my memory of the 90s Fowler is a bit hazy.
Fowler by a nose.
Fowler is head and shoulders above the other two, Torres had a very good first season which he has lived off ever since even though has continued to score goals but not as many due to being injury prone. I think attitude plays a part in it too and Fowler again comes out on top as the other two have been a disgrace in this department.