My personal opinion is that both sides are in the wrong here. Israel is overstepping its borders, but Palestine is not controlling Gaza and isn’t exactly cracking down on the extremism or defending their borders. Israel is taking advantage of the weak, poorly organized, poorly administered Palestinian (and Syrian!) land by annexing small plots slowly over time.
If you talk to Palestinians, they want to return Palestine and its lands to a Muslim country. They have an overall nationalistic view that I don’t find conducive to peace or overall benefit to everyday people.
As a general idea, I’m all for self determination, but I’m also for the rule of plurality. Because of that, and Israel’s general secular liberal principals (not in the modern American definition of the term), I side with Israel.
My genuine gut feeling is to benefit the most amount of people possible, and thus support the side that more closely adheres to the declaration of human rights.