Now I'm using Howard, Moulton, et al.'s reference grammar (only volumes 2 and 3 because 1 is really really basic, and vol. 4 is supposedly controversial).
I had used Robertson while at seminary, but never bought it. I did purchase Blass - deBrunner and have used that extensively, even though it is somewhat dated. I also had the four volume set Howard, Moulton, and Turner, but gave it to a seminary student about 7 years ago. Turner offered some interesting twists on understanding the text. I also have his book,
Grammatical Insights into the New Testament, and have found it refreshing to say the least.
I have twice read through
Linguistics for Students of New Testament Greek: A Survey of Basic Concepts and Applications (1988) by David Alan Black, which focuses on a different part of learning and understanding Greek.
And, of course, for the relationship between semantics and Biblical studies the best is
Biblical Words and Their Meaning: An Introduction to Lexical Semantics (1994 rev. ed.) by Moises Silva.
Three other books that I think are indispensible for NT studies are:
Exegetical Fallacies (1996, 2nd ed.) by D. A. Carson. Even those who do not know the Biblical languages would be well-served by reading this one.
What Does This Mean? Principles of Biblical Interpretation in the Post-Modern World (1995) by James Voelz. He deals with textual issues, semantics, and interpretation issues. Excellent book. (He was my final post-graduate advisor, after my professor died, prior to my finishing).
Multipurpose Tools for Bible Study (1993, rev. ed.) by Frederick Danker (of Bauer-Danker-Arndt-Gingrich fame). To me, for any serious student of the original languages, this is a must because he provides a list with detailed explanations of the various resources available for serious study in the original (and early textual) languages.
---
If you are interested in Septuagintal studies and the Greek language, there is
Invitation to the Septuagint (2000) by Karen Jobes and Moises Silva. You can wade in the pool, or take a very extended deep-sea dive in this book. Very good. I have read it once already and will soon go back for a second swim.