I almost always stay at the Holiday Inn Ariel (because of IHG status, although the Ibis virtually next door works almost as well) because if I walk for no more than two minutes I can access a direct free bus to any terminal - albeit less frequently to T5, and often it's quicker to take the Central Bus Station/Tube option where the transfer is quick and pretty much painless. 105/111/285/N9 for T2/3 and Tube for T5 connection, 423 to T5 from Harlington Corner and 555 to T4 from Hatton Road North.

Clearly much cheaper than the Hoppa, and certainly considerably quicker too - even to T5 it's no more than 30 minutes including any wait time, and usually 20. T2/3 is something closer to 5 minutes given how many buses go down the Bath Road to there.