It says somewhere around here that the smoothies were cut from the SEN lounges in FRA, so I wouldn't go through FRA for that. As far as which to choose, I would go with the one with the easiest transfer setup. Since I don't know what operations are like right now at FRA and ZRH for EU-TLV flights, someone else has to answer that.
Both has it's pros and cons.
FRA is an awful hub to connect in and the plane to Tel Aviv is always on the far end of concourse C. So you are looking at a long walk with several sec checks. Or when using the airtrain queuing up at understaffed sec points.
ZRH is really nice, small and easy to connect from. But you run the risk on ending up not in international C cabin but on euro c, which is basically an y-seat in a 3*3 config with the middle seat left empty. Happens from time to time that LX uses another plane to go to TLV
So investing miles into an upgrade award and ending up in a euro c seat, I seriously would hate that.