The problem here is defining the term 'best' and I suspect it will never be agreed to everyone's satisfaction. The three nations refered to already, Britain, the US and Isreal are all very different Army's born out of different histories, doctrines and, perhaps most importantly, out of different budgets. I have never had the pleasure of serving alongside the Isrealis (although I once met the most beautiful female Armoured Infantry Company Commander), but I have spent some time up at Fort Lewis with the Americans.
My experience was that the US Army is just different from the British Army, better at some things, worse at others. Their logistical chain and use of close fire support is something that we 'borrowers' can only dream about. Their mobility around the battlefield, on both ground and air, enables them to be able to, if they had the inclination to, fully employ maneouvre warfare in its purest form. They do however have their weaknesses. They are not particularly good at 'thinking outside the box', not are they able to switch from warfighting to peacekeeping at the drop of a hat, something the Brits are the best at the world in due to policing the Empire and the last thirty years in Northern Ireland. Certainly I got the impression that force protection in the US Army was paramount whereas in the British Army it is balanced against setting the local population at ease and winning them over to you.
Maybe just different Armies, with different strengths and weaknesses and different mindsets.