Dont know about BA WT+ but I would be hesitant about wasting money on the QF PE. Flew SYD-BKK in November and decided to try out PE, seat ok, cabin service was good but the meal was slop in a bigger tray. Two of us were travelling together and we asked for opposite aisle seats at check in, to be told sorry its full, on board however, there was us, and 5 other people. Qantas has REALLY gone downhill.
I have to say the same about PE.
The meal was worse than anything I've ever had in economy in the last 10 years - the main course was bordering on inedible, and I am not a fussy eater. Hopefully it is not representative of QF PE meals but it was certainly unimpressive and put me off somewhat.
I also found that the seat did not suit my body shape and found it to be just as uncomfortable as economy class, just in a different way.
So, for the price difference, I decided that I'd sooner have the exit row aisle seat in economy than a normal PE seat.
I'm flying WT+ on BA soon so I'll get to make up my mind about that, but I have the suspicion that I will find it not worth it. I only booked one way WT+ in case I don't like it.