In essence TTWE is the most radio friendly, but they should have tried something more fresh like Inside Out or I Wanna Go. Those songs are more Britney while TTWE is more Brit/Ke$ha. At least thats how I feel.
IDK. This era's a bit of a mess. I guess I Wanna Go is the best option now since it's already debuted. I love Big Fat Bass but it didn't show its potential.