You're not going to get a single straight answer.Are they basically a wash when you consider Espresso advantages(OoE) and more cache vs the higher flops and more instructions per cycle(due to 128bit ect ect)?
If you come up with some kind of chaotic program made up of constant ridiculous unpredictable branches, espresso would quite possibly beat Xenon and CELL by a fair margin. On the other hand, if you're looking at a computationally-heavy section of code which carries out lots of parallel floating-point calculations, I wouldn't be surprised to see Xenon stomp on espresso (and depending on what you're doing, CELL might very well totally wreck both of them).
In the real world, the answer probably depends on the makeup of your game code.