They're two completely different sports that just happen to involve hard hitting contact and an oval ball.
Union is a much more rounded game, where players must master a number of skills, and inevitably they're not going to be experts in everything. I prefer this mixture because I think it produces the group of men who collectively cleverer, faster, fitter, stronger and more skilled than their opponents. If you want an analogy, it's the same reason I think mixed martial arts (eg UFC) is the purest form of fighting, because the champion will be a master of many disciplines.
That's not to say that Union is a superior sport. It just gets me more excited.
It's obvious that American Footballers hit harder in the tackle in terms of pure force. If they hit that hard without protection none of them would last more than a few years and they'd break bones frequently. But that's what the sport demands; the same reason RL hits are more brutal than Union because the aim is not to gain possession afterwards; it is essentially to knock the opponent as far back as possible to prevent territory loss. The fact that in AF defenders come from all angles, travelling at great speeds, hitting all parts of the body and with the psychological knowledge that they're wearing protection, makes the hits much harder.
A Union guy on the other hand has got to make 10+ tackles per game, in the mean time hitting contact when he's in possession; at scrums, rucks and so on. So obviously he can't commit or recieve a huge number of heavy tackles in one game because he needs to preserve himself over 80 mins.
It's obvious that American Footballers and also League Players have a higher skill level than Union. This too is because the players have much less to perfect. A League centre will offload better, run better angles, and have better handling skills.
So if you prefer a highly tactical game that is full of short, sharp bursts of immense speed, power and skill but takes hours to complete, then American Football's your game.
If you prefer a more fluid game with wonderfull ballskills, physicality and pace then League's your game.
And if you prefer a totally fluid game with less concentrated doses of physicality, pace, skill, tension and so on the it's Union.
It really isn't worth arguing to get one over on the other sport, because they all offer different things that different people will value more. Besides, I'm pretty sure most of the arguments stem from stupid North-South or Anglo-American one-upmanship anyway.
