It's absurd to assert that most "staff" in the Middle East are slaves ffs. Most of them are here by choice and come back year after year 
Yes, things are different here. Yes, there could be vast improvements. But people act like all the women are chained up at home and all the foreign workers are being abused. It's not the case at all. And I live in the "worse" country next door. The millennial and younger generations here are fantastic. Open, educated, determined - hopefully they will drive change in a complex part of the world. Do people forget that the USA still has the death penalty?
OP it depends what sort of holiday you're after, truly. I wouldn't go to Dubai for a beach holiday personally but there's loads of activities around there and Abu Dhabi. Theme parks, water parks, desert trips, skiing, Burj Khalifa and Arab, sky diving...
Oman is a different vibe entirely. Doesn't have the glitz (but plenty of lovely hotels), less contrived, but also less "stuff" more nature. Lovely wadis to swim in and explore, nice beaches, mountains, traditional feel.
Jordan is fantastic for historical sights.
Wouldn't bother with Bahrain/Kuwait/Qatar.