I want to recommend to you the possibility of reading books not from front to back, but rather by reading it by inspecting the index and reading across the book all sections that belong to the entry of interest.
Though you explicitly excluded books organized by 'dead person', I'd like to recommend to you Bertrand Russell - A History of Western Philosophy for that purpose.
It is a very excellent overview of, as the title says, the Western Philosophy, from the antiquity to 1945.
As mentioned above, you can work through the topics by looking at the index, e.g. for existence you find there
existence, 752, 785; and Aquinas,
446, 447, 453; and Kant, 568, 682;
and Leibniz, 567, 569, 574-5; and
Locke, 675; and Plato, 167-8; and
Socrates, 149-50; struggle for
I'd say that is some quite good overview, as you can directly see, what topics very different philosophers approached, what topics raised more attention, and also you can see quickly the importance of philosophers by the length of their entry and their reception of other philosophers, see eg the entry for Epicurus:
Epicurus, 82, 83, 249-59, 356, 387,
729; and utilitarians, 742, 743
You can see that Epicurus influenced later traditions as he appears throughout the book, and you can already see that there is a connection to utilitarianism.
This way is not providing you a nice, consumable synthesis of the different branches of philosophy, as you required in your question. But I would argue that it is not a good idea to try to consume philosophy anyway. Rather you should really try to work on building a synthesis yourself, as only in that way you can gain a deep and true understanding of not only philosophy, but practically anything.