All of them, though not all of the time. When I was younger I would seasonally go through different periods of interest in US history and that has expanded to engulf the whole of human history (and before. Yes I love evolutionary biology). Last summer I was binging videos on evolution and natural science and now I am prowling YouTube comment sections to argue with Lost Causers.
It is folly to single out a single century, for one century builds on the next and to ignore what came before removes vital context for how you got there, removes the contemporary context and what was on their minds and governing their actions in that given period and finally it makes things seem almost unheard of or unprecedented when in reality such was merely a cyclical occurrence or otherwise recedes into the backdrop when presented alongside similar events.
I have favorite events that tend to occupy most of my attention and in every case, I end up drawing on decades and even centuries prior to provide the appropriate context and basis for the events in question.
The Long 19th Century (1789-1914) has always been my favorite.
That would be #1 on my list of most overrated centuries. It's frustrating how much attention the 1800s gets, while the more than 100 years between the end of the 30 Years' War and the start of the 7 Years' War is largely neglected. I've just always found struggles of ideology and nationalism to be far less intriguing than dynastic power politics. The period encompassing the late 17th and early 18th centuries - with its constantly shifting alliances, wars of succession, and conflicting political and religious interests of the various states - was truly the peak of European diplomacy and grand strategy. Not to mention the peak of art, music, and culture on the continent.
Personally, I could never much bring myself to care which wealthy Italian family was currently king of the hill or which royal cousin has the more "legitimate" claim —none of those people would have been interested in me. I do agree that the late seventeenth/early eighteenth century has a lot to offer, though.
Wealthy royal families don't have time to be interested in plebs, Truman. They are far too busy with more important matters, namely making the plebs fight to defend their legitimate rights to the throne of Spain/Austria/Naples to worry about such provincial concerns.