so I saw
this rating Vienna as having the best living standard and Baghdad as the Worst, so with a post 1945 POD flip that around
Baghdad becomes the capital of a unified Hashemite state of Iraq and Jordan with Kuwait shortly there after being coerced into the fold. The Jordanian branch ultimately ends up in charge owing to a series of unfortunate events, which are eventually put down with covert American support. Said monarchy manages to ward off the unrest of Arab nationalism, and gradually liberalizes.
Iraq is seen as a vital American ally during the cold war and receives billions of dollars worth of technical, military, and logistical assistance. This aid helps to establish a modern military, a modern system of infrastructure, and a modern petrochemical industry. Competent leadership also establishes nearly universal literacy by the late 60's. These ties are further cemented by a generation of princlings educated in Harvard.
Iraq remains very much an oil state and its exports rival that of Saudi Arabia however its an oil state with a large growing middle class. Close ties with America, starting in the 80's begin to bring a new added benefit. Baghdad rather than Riyadh becomes the principal site for Corporate American branch offices in the gulf. Arabic startups begin to emerge, and grow and several multi-billion dollar domestic firms emerge headquartered in Baghdad. This super charges the city's economy, and gradually it becomes the commercialcenter of the middle east, and ultimately one of the worlds principal financial centers.
As for Vienna, have it be completely leveled by siege during WW II. The city and east austria undergoes a Prussia like fate, as its citizens are deported and replaced with settlers from a dozen different ethnicities. The new Vienna is a concrete and cinder-block monstrosity dominated by obsolescent heavy industries and the looming presence of the russian military. When the soviet union falls, a communist hardliner retains power for another few years. By the time he is deposed, the state collapses into internacine civil war fueled by drug smuggling and other such black market activities. The resulting city is thus a complete hellhole, deserving of this ATL's worst living standard.