need a phablet replacement for my S4

[WuddaWaste]

No no no no no. The Star S7589 was really cool like 2 years ago. Don't get it now! It's now officially old and crappy. Don't buy a Star S7589!

This website shows Israel as having 2G running on 900 and 1800 MHz. 3G runs on 850/2100. Is that correct for your cell service?
http://www.worldtimezone.com/gsm.html

If so, I have absolutely no hesitations in recommending the THL T200 (or T200C, which is unfortunately no longer available most places) for consideration. It's a 6-inch phablet that has treated me very well. Here are some links to them:
http://www.merimobiles.com/thl-t200_p/meri10243.htm
http://www.gearbest.com/cell-phones/pp_23085.html
http://www.coolicool.com/thl-t200-mtk659...ne-g-32883

If you're seriously considering a OnePlus One (and you should -- it's a wicked cool phone), it's in the slightly smaller range at 5.5 inches. Amongst those the Doogee DG550 has been popular as well as the iNew V8. Neither are as powerful as the OnePlus or T200, but I've bought and used both. I recommend the Doogee first if you're in Israel, but they're both solid choices.

I'm sure there are others to consider. Hopefully more people will chime in with what they have and like, too.

By the way, very cool field of study. And very cool job. I like your style, friend!