Ronald Grigor Suny has written extensively on the Caucasus, including specifically about Armenia (his father was an Armenian from Tbilisi), and I'm also a bit of a fan of his work. He's written two books on Armenia, though they are more focused on the twentieth century:
Armenia in the Twentieth Century (Scholars Press, 1983)
Looking Toward Ararat: Armenia in Modern History (Indiana University Press, 1993)
Stay clear of Paris Herouni's "Armenians and Old Armenia". This is the one book in English I've seen and it was a quagmire of /r/badlinguistics, /r/badarthistory and /r/badhistory.
I dug deeper. And I discovered what?
There was an explosion of nationalist mythmaking starting with the 1980s which was footing on the idea that the Soviet Armenian historians were all conspiring to undermine the national consciousness of the Armenian people promoting instead the idea of a common Caucasian history.
In the Russian wikipedia there is an overview of this controversy both before and after Armenian independence. But there also is this article in English written by a historian who traveled to Armenia in the 1997 which gives a very good hands-on idea of what and how it went wrong.
The current classic acceptable to the Armenian intelligentsia is Հայ Ժողովրդի Պատմություն (the History of the Armenian people) written by the historians of the University in Yerevan during the 1970s. Tome 1 is an overview of the stone and bronze age, urartu, the Armenian state in the early Hellenic era, Tigranes II, the conflicts between the Romans and the Parthians, the end of the Artashesid dynasty and the beginning of the Arshakids. Last chapter is devoted to the culture and economy in the 3rd-4th century, i.e. the times covered by the first domestic sources. Tome 2 covers the middle ages, starting with the introduction of the christianity and the fall of the Armenian state, then it covers various rebellions, expat communities, the literature and the arts, the mongol invasion, Cilician Armenia and the relevant parts of Byzantine, Turkish, Persian and Russian history. Tome 3 covers the 19th century Armenian question both in Turkey and in Russia ending with chapters on the independence and on the genocide. tome 4 covers the Soviet Era and should be taken with a trainload of salt. I linked it in Armenian but here you can get it in Russian. If there is an English translation out I do not know. Write to the university of Yerevan.