We often hear about judging western historical figures, usually American founding fathers, by “modern standards” and the general consensus seems to be that we should, as the people they conquered and enslaved did not wish to be conquered and enslaved. But does that apply to non western peoples like the Ottoman Empire. Yes they were tolerant compared to the dismal standards of Europe, especially their arch rival Hapsburg Spain, but at the same time their armies massacred entire cities, conscripted young boys into their service, forced women from conquered people’s to become sex slaves, and the Sultans regularly murder their infant brothers upon accession. Again I don’t want to indulge in “terrible Turk” propaganda. They were doing all this at around the same time their rivals were preforming such atrocities as the Atlantic slave trade or wiping various native cultures off the map. But the question still stands, should we still glorify the Ottomans, or should we heap the same scorn upon them that “problematic” western historical figures like Thomas Jefferson revive, or is there a way in between. Sorry if I ramble or if I got too political.
Ottoman studies is extremely obscure compared to most other fields in American academia, and it's a subject that most Europeanists don't really examine from the Ottoman side because the language requirements are incredibly difficult (Ottoman Turkish, Arabic, Persian, and then potentially Greek or a Eastern/Central European language). The presence of a non-European Christian empire being the nearly undisputed military superpower of Europe for about two centuries also inhibits facile and anachronistic projections of European=oppressor and non-european=victim. This is based off of projecting 19th century imperialist conditions and European military supremacy in that period onto the early modern world. It wasn't the case at all during that era. You are also absolutely correct that the empire was responsible for an immense slave trade that covered North Africa, Eastern Europe, and Eurasia that ran parallel to the Atlantic slave trade. But this is a topic that is left out of many public school or college classes because of its relative obscurity (in the US) and that for some reason discussing this makes people uncomfortable.
The Ottoman Empire is too obscure and complicated a topic for most people, and even most contemporary Western historians, to be interested in let alone think deeply about, precisely because of the reasons you mentioned. Ottoman tolerance also had limits and was nothing like what we today would think of as freedom of religion. Christian and Jewish subjects were tolerated and allowed to practice their religion, but they were still second class citizens. For example, Christians could maintain a church in Ottoman territory but could not build a new one. Unfortunately, popular pundits and some pop historians like to spin this as a simplistic case of the "enlightened" Islamic world versus the backward Christians. Personally, I believe this is a far more damaging Western, Orientalist gaze as it deliberately obscures uncomfortable aspects of the Muslim world in service to a particular ideology. Even worse is that this reduces Ottoman and Islamic history into a rhetorical tool and makes the topic less attractive to potential students or the public.
As an Ottomanist myself I think we should examine the past frankly and assess the empire's legacy in a balanced manner. The Ottoman Empire created a tremendous civilization and unique culture, but I do not believe that that means I should whitewash negative aspects of it. History is very complicated, but that is a difficult thing to communicate when people want neat and clean narratives that affirm their ideology.