I don't know why, but research on Dál Riata (Dál Riata) for the last half century has apparently tended to be published rather in journal or book chapter rather than in form of monograph.

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• Fraser, James E. From Caledonia to Pictland: Scotland to 795. Edinburgh University Press, 2009. http://www.jstor.org/stable/10.3366/j.ctt1r28q5. The New Edinburgh History of Scotland 1.
• Woolf, Alex. Woolf, Alex. From Pictland to Alba, 789-1070. Edinburgh University Press, 2007. http://www.jstor.org/stable/10.3366/j.ctt1r24g0. The New Edinburgh History of Scotland 2.
• Márkus, Gilbert. Conceiving a Nation: Scotland to AD 900. Edinburgh University Press, 2017. http://www.jstor.org/stable/10.3366/j.ctt1pwt3ch. The New History of Scotland 1.

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Have you checked these volumes? They are a part of two current series of Scottish history, based on the research status of the 21th century. Fraser's and Woolf's incorporate fruits of the newer articles appeared in journals and collection of essays in the last decades, and especially the former has authored some of them by himself. They also have further reading section, and [Fraser 2009: 391] is specially dedicated on Dál Riata.

On the other hand, while Márkus' might be a little weak in political history, the book makes it up with elaborated chapters in the church and the society.

Alternatively, Dál Riata is more extensively featured in the older edition of the New History of Scotland (sorry for so confusing), Alfred P. Smyth, Warlords and Holy Men: Scotland AD 80-1000, Edinburgh: Edinburgh UP, 1984 (apparently mainly based on [Bannerman 1974]), with detailed reading guides up to the beginning of the 1980s (Smyth 1984: 246-48).

So, the classic on the topic as a monograph is apparently still: Bannerman, John, Studies in the history of Dalriada, Edinburgh: Scottish Academic Press, 1974.

Newer research mainly in form of articles and book chapters by Fraser and Dumville mainly focus on the re-reading of the key texts like kings' list, or archaeologists like Ewan Campbell raise doubt on the impact of the Irish emigrants in early medieval Argyll. Campbell summarizes his challenging new view also in the concise introductory book, Saints and Sea-kings: The First Kingdom of the Scots (Making of Scotland), Canongate: Historic Scotland, 1999.

• (Edited): corrects the format of the bibliographical list.
• (Edited): fixes the broken link to [Woolf 2007].