I rate the English and Australian infantry far higher than the US - only because their training is better (time / structure). Sadly both of these forces are small, poorly funded in the case of Australia. We have the poms to thank for setting up a good defense force ... their CSM's are trully mean bastards ... and I mean that as a compliment.
Having spent some time with them back in the 80's and hearing the experiences of my two uncles in Nam, I don't rate their regular ground forces very highly.
Morale is poor without all of the trappings of home and they have undisciplined response to small arms fire, have poor training, and are only trully a force to be reconned with when their superior technology is deployed, and superior numbers.
Plus their air support is just humiliating to be on the wrong side of!!
I rate the marines about the same as the regular army as their training is comparable but conditions of employment are tougher. Many think the US army is better than the marines because their conditions of employment are better but I argue the opposite - tough love breeds a tougher soldier.
The US special forces are on par with the best in the world - plus they haz more tech and cool gadgets.