I've never heard of noise problems from the tube tracks.
If you do choose the Earls Court location....look into spending a little more for their "Plus" rooms. They are recently renovated and have a real coffeemaker and a mini-fridge.
Don't waste your money on their breakfast. For a full English, go to the Blackbird pub just one block away where it will be made fresh to order rather than the food sitting under heat lamps for who knows how long.
For just a "continental" type breakfast, head to "Paul" which you will pass walking to the hotel from the tube station. Excellent pastries and breads. (it's a French chain.) There is also a Pret a Manger for pastries and some breakfast sandwiches right next to the entrance of the tube station.
For a more "health" oriented breakfast, try "Over Under Coffee" on Hogarth Road. It is just past Paul and around the corner.