Which language is preferable for speaking with Palestinians: Hebrew or English?

Use English, period.

Not that using Hebrew is the problem, but why use the language of the people whom Palestinian see as the people who took their land? use the language that will make them feel respected, their own mother language.

In addition to that, unlike "1948 Arabs" who live in Israel and they are mostly bilingual, the general Palestinian population do not necessarily speak Hebrew. They study it in school, even in Gaza, they can manage (usually to be able to communicate with the Israeli soldiers). Many who have worked in Israel in previous times when it was allowed, or imprisoned there do speak it fluently, but not all.

Palestinians are friendly with foreigners, many (especially in the west bank) do speak English, it's after all a touristic area (area A).

Regarding the similarities between Arabic and Hebrew, there are a lot of similar words but you will need to hear them slowly to understand, and both use the same concept of word roots. However, current Hebrew lost many of its Semitic features (grammar and sounds), Arabic is kinda more Semitic than Hebrew as Hebrew is heavily influenced by Europeans languages.

Here are some words that will help you:

• Marhaba or Salam: Hi
• Tetkallam Engleezi?: Do you speak English?

I am an Arab but not Palestinian, I know a lot of Palestinians and we have had long chats about this in a few occasions.

It depends on where you are. I frequent stores in an Israeli commercial center where Palestinian Arabs are welcome, and in fact many employees and customers of the supermarkets are Palestinians. (from Ramallah and the surrounding villages.)

On numerous occasions I've struck up conversation with the Arabs- basic polite discourse about where to find an item, or regarding parking/shopping carts etc.

Although I'm a born Anglo who speaks Hebrew with an accent, I've stopped talking to them in English since they almost always feel more comfortable talking to me in Hebrew than in English. Occasionally one will want to practice their English with me, and I'm happy to oblige, but it's rare.

On a couple of occasions I've been in cars where the drivers have stopped into the villages near the Hizma checkpoint into Jerusalem (like Hizma and Michma'as) to do some shopping. In these villages as well, they've preferred speaking in Hebrew over English to me.

I'm sure there are places where they on principle won't speak Hebrew; and it could be very different it you clearly are a tourist as opposed to an Israeli.

In my examples, the Palestinian Arabs are employed and engaged in commerce with Israelis. If you go to villages which don't have as much commercial interaction with Israelis, you'll probably find more English and less Hebrew spoken.