USA ! USA !
No but really they have the most advanced armies, if they would resort to cowards tactics like the rebels in the middle east do, they'd wipe out the whole population of a country faster than any other army.
Sorry but the UK has no chance vs the US:
Soldiers: US : 1.4 million, UK 165k
Reserve troops: US: 1.4 million UK : 233k
US's defense budget is 10x as high as UK's.
US has +- 7k tanks, the uk only 1k
The US navy is nearly 5 times as big if not bigger.
US has 2600 air units, the UK only 504
And the US has a 46 times bigger nuclear arsenal.
People keep skipping my good point.
How are you getting 1.4million troops, enough tanks on to the british isles?
Any plane would be shot down and coastal defences would be set up well in advance of them getting to our beaches.
Nukes however, is almost like cheating, both have enough to do serious damage.