We have a D-8H dozer and a JD644 wheel loader . I think its easier to level with the cat and it will push more dirt buts its twice as many horsepower. The wheel loader will do the same job just slower and you have to dump the bucket . I really like the loader for small jobs and being a wheel loader its easier to  get to the jobsite. I really do not care for a track loader because it has all the disadvantges of both type machines, unless you are doing demolition work.