Agree with previous posters - I've used Jury's Inn at Hatton Cross a couple of times: clean, quiet & comfortable enough, and seems better value than other hotels. Could never find any decent deals on hotels at terminals (Sofitel T5 & Hilton T4).

Closeness to tube means no need to use those Hotel Hoppa buses which are not cheap, not that frequent and can get stuck in traffic. Breakfast is extra there, so filling up in lounge is good option.