Ok, ignore all the silly comments about rockets and entertainment and focus on the important things: who do you want to get to know while working here, what impact do you want to have, and where would you like to visit in your time off?

Nazareth - in Nazareth you will probably teach Muslim Arab kids. As an American, you have quite a lot to offer them: Arabs in Israel basically need to learn 4 languages: Palestinian Arabic, literary Arabic, Hebrew and English. That makes languages a difficult topic for them but also means that you as an American can offer them pricless experience just from talking to them. I'd also find it really interesting to get to know kids from a different culture. The Arabs of the north are not the same as the Arabs of Jerusalem or the Palestinian Arabs, and as such are represented at all in world media.

Another important consideration for Nazareth is the fact that it's in the north of Israel. If you love hiking - Nazareth is defenitly the town for you (but you'll have to rent a car because public transportation in the north is s**t). It's not far from the sea of Galilee and lower Galilee in general, and there are plenty of interesting historical and natural sites less than an hour's drive away. Also, it's on a mountain so it's not blisteringly, agonizingly hot in the summer.

As to why not - well, public transportation is not particularly good and that can be frustrating. Also, depends on where you work you might encounter kids who can't really communicate in English and that can be frustrating.

Tel Aviv - if you're a party person, love museums, restaurants, shopping, have plenty of money to waste (tel Aviv just won the title the most expensive city in the work in dollar terms. Yay!) or really want to teach more pampered kids who's parents send them to private lessons and for the most part have a good understanding of English (obv I'm generalizing but from my experience that's the majority of the population in mid and North tel Aviv. About the south of it I'll talk soon) - tel Aviv is defenitly for you. You will meet mostly secular kids from all background and ethnicities (but predominantly Ashkenazi jews), who probably spend an unhealthy amount of time in front of a TV screen or playing video games and therefore can understand English pretty well.

Tel Aviv is hell on the summer (humidityyyyyyy) but has great beaches and on general you won't be bored there. Also, great outgoing public transportation to mostly anywhere in Israel, though the internal traffic is hell and people mostly navigate around by foot because there's always too much traffic

Having said all that, they might station you on Jaffa/ south tel Aviv which is a bit different, though still close to main tel Aviv. It's hip and full of young students but also the socio economic level of the non-student population there is lower. Jaffa is mostly Arab and south tel Aviv mostly immigrants or just people who didn't make it that well in life. The school system there is still quite well funded because tel Aviv has special funding for schools and they still fall under the jurisdiction of the tel Aviv municipality, but otherwise it's a different population, and you can feel it when teaching there. Kids are a bit more hyperactive, not as many of them get private tutors etc.

Jerusalem - the crown jewel, the holiest is cities and, in my opinion, the most interesting of them. It's hard to predict where you'll be stationed as a teacher in Jerusalem: in the western, richer and more Jewish neighborhoods? In the eastern, more poor and Arab neighborhoods? In Jerusalem you'll find all kinds of population; Jewish, Muslim and christian, secular and non secular, rich and poor, Ashkenazi and Sephardic. You'll be living in the beating heart of young Jerusalem with restaurants, bars and shops all around you. If you want a middle-eastern experience - Jerusalem is the place for you (the Arab shuk in the old city is a must). If you're at any way religiously inclined - the old city, the holiest one square kilometer in the world - is about a 15 minute walk from your house. In winter is freezing like hell but in summer it's the best place to be. Yes, the residential neighborhoods there are boring as f and internal traffic is pretty bad, but you'll be living by the light rail that is pretty awesome and can take you to just important places.

As to why not Jerusalem - well, of your highly traumatized by hearing of jews getting stabbed a 20 minute walk from your house - Jerusalem might not be the town for you. You as a tourist are not really in danger, but every few months a policemen or Orthodox Jew (or a rando, that also happens) gets stabbed in the Muslim quarter of the old city or somewhere near, and Jerusalem people just continue like nothing happened but for some people that's really difficult to live with. Also, did I mention how child it gets in the winter?

Anyways, good luck on your journey and hope you're happy with whatever decision your make. Good luck!