Please point me in the right direction, thank you!
I quite like April DeConick's work - mainly articles on her site, though she's also the author of Recovering the Original Gospel of Thomas: A History of the Gospel and its Growth and Voices of the Mystics: Early Christian Discourse in the Gospels of John and Thomas and Other Ancient Christian Literature.
She's one of the folks who believes that Thomas was (partially) written prior to the canonical gospels, and that John especially has traces of debate between a proto-gnostic community and other early Christians.
Bart Ehrman is the scholar who writes best-sellers about early Christianity.
He's got an upcoming book called Jesus Before the Gospels that might be up your alley; his Lost Christianities probably covers a lot of ground you'd find useful.
(I haven't read either, but found some of his lectures really interesting.)
Speaking of lectures, Dale Martin's Yale course is great.
Elaine Pagels is also a scholar with a popular draw - her The Gnostic Gospels was pretty important in sparking public interest in Nag Hammadi and early Christianities. Her more recent Revelations: Visions, Prophecy and Politics in the Book of Revelation uses Revelation as a kind of window into religious politics of the period.
She's a little bit on the Gnostics=plucky, Mainstream=oppressive side of things.
You might get some good answers to this question if reposted in /r/AcademicBiblical .
Michael Allen Williams "Rethinking Gnosticism: An Argument for Dismantling a Dubious Category". He argues that the "gnostic" category in reference to Nag Hammadi is rather dubious and that a better way to think of this continuum of religious movements is "biblical demiurgical traditions". He also argues that they weren't altogether unified in a single "gnostic" vision either.