I do both as well. They're both equally as interesting as each other to me, but I'm doing a hell of a lot better in Food Tech because there are less to compete with than PDHPE. In saying that, it's most likely you will attain a 90+ with Food Tech like myself with moderate study paying close attention to the syllabus. PDHPE requires A LOT of study (which is why I'm only sitting on an assessment average of 85) as the syllabus is enormous - will probably be shortened for you next year.
Most of the time, PDHPE gets scaled down if you get below 85... Where as Food Tech never really gets scaled down because it's quite difficult to do horribly
I'm expecting a state rank for Food Tech myself, and somewhere between 98-100 for the actual HSC exam (due to the huge study gap between my last two exams). The assignments for Food Tech are relatively easy as they focus solely on each topic, so just make sure you look at your syllabus to sufficiently address the marking critera. PDHPE varies in assessment, and I did poorly in one which completely fucked up my rank because I didn't read one word ==" Oh well.
Up to you, but if you can't do both I would suggest Food Tech most definitely. It also depends if you get a good teacher (mine was the head of Food Tech for 10 years and a senior HSC marker) Will definitely keep in contact after HSC ends
So I was lucky there and motivated to do well.
Whatever your decision, Good Luck! consistent study is better than short, huge amounts (I learnt that a little too late)