Ive used both, my experience suggest Ecover is better. Does a more thorough job.
Im sure TFR cleans, however I always thought it was meant to be used as a restorer, to clean those ingrained dirt stripes and areas at the end of sills that always seem to be greyer than the rest of the plastic.
I dont think Ecover does that, but in general as a cleaner (for what I use it for) its much better than TFR.
Matt