I suppose we all know that Acts can't be earlier than c. 62 CE (since that is when its story ends) or later than Irenaeus (the first to explicitly mention Acts) in the mid to late second century CE. And I assume most people here see Acts as being post-70 CE, but if an earlier date floats your boat then have at it.
So when do you date Acts and why?
As for me (and feel free to ignore it, as I've said it a number of times before elsewhere), I've been stuck on the idea that Acts was written c. 95 CE by Paul's friend Epaphroditus, who is mentioned in Php. 2:25-30.
But I thought it necessary to send back to you Epaphroditus, my brother, fellow worker, and fellow soldier, who is also your messenger and minister to my needs. For he has been longing for all of you and is distressed because you heard he was ill. He was sick indeed, nearly unto death. But God had mercy on him, and not only on him but also on me, to spare me sorrow upon sorrow.
Therefore I am all the more eager to send him, so that when you see him again you may rejoice, and I may be less anxious. Welcome him in the Lord with great joy, and honor men like him, because he nearly died for the work of Christ, risking his life to make up for your deficit of service to me.
Paul mentions him again in Php. 4:18 and he is the last person mentioned by name before Paul says in 4:22, "All the saints send you greetings, especially those from the household of Caesar."
This makes me think that he could be the same Epaphroditus who was Nero's secretary who was executed ,c 95 CE during the time of Domitian's persecution of those who had "drifted into Jewish ways" (as Cassius Dio puts it). And I think this could also be the same Epaphroditus who became Josephus' patron. And if so, then this could have been someone who knew Paul and Josephus and had access to their writings (with the latter appearing to be the case in any event, as per Pervo).
In Josephus' preface to the Antiquities, Epaphroditus is described as:
... a man who is a lover of all kind of learning, but is principally delighted with the knowledge of history, and this on account of his having been himself concerned in great affairs, and many turns of fortune, and having shown a wonderful rigor of an excellent nature, and an immovable virtuous resolution in them all. I yielded to this man's persuasions, who always excites such as have abilities in what is useful and acceptable, to join their endeavors with his.
Why couldn't Paul have been one of these other people "such as have abilities in what is useful" that this Epaphroditus had joined "endeavors with"?
The Epaphroditus in Paul and the one in Josephus both had "turns of fortune" and showed "a wonderful rigor of an excellent nature and an immovable virtuous resolution in them all," Paul's friend because of his illness and recovery and work with Paul, and Josephus' patron because of whatever his "turns of fortune" were, which could certainly include recovering from an illness and working with someone like Paul.
And since Josephus' Epaphroditus was above all a lover of history and had access to Josephus' writings, he seems like a good candidate for the authorship of Acts to me. And if this is the same Epaphroditus who was Nero's secretary (in keeping with Paul's association with "those from the household of Caesar," who at that point was Nero), then Acts could have been written no later than c. 95 CE, when this Epaphroditus was executed.
95 CE doesn't seem that far from the mid-second century CE to me. It's a difference of as little as forty years or so, and only twenty from Pervo's dating of c. 115 CE. And while a later date is fine with me, I don't have any guesses as to who could have written it then beyond someone with access to earlier NT writings and Josephus. It could be anybody, even Ireneaus, for all I care.
I've never been persuaded by anti-Marcionite arguments though, but if that's what works for you as far as dating goes then have at it and I'll give it consideration. Or just give a date and no reason for it, since this is intended as more of a survey of views here than a debate.