After doing a bit of reading around the subject I've come to the conclusion that the FE figures are so much better because they were designed under the Generations brief, as that was the line they were originally meant to appear in.
That was before the DOTM which brought us sparsely painted oversimplified figures with big F off guns using so much plastic that it necessitated that the core figure was smaller and less complex. TFP's mainline appears to follow this - all the figures are smaller and less complex than their FE counterparts. For example,
Bumblebee and
Cliffjumper.
That and the cretinous new names for size classes (Weaponiser? Please) means I'll be passing on most of this line.