The problem is that they are seldom readable. While some grammars may be good for reference (like BDF and Robertson) you would be hard-pressed to sit down and read them through cover to cover. They’re just not meant to work that way.
When I saw Richard Young’s Intermediate New Testament Greek: A Linguistic and Exegetical Approach, however, I had hope. It was a manageable size (308 pages) and actually looked like I could sit and read it (no, really, check the sample scans at the bottom of the product page).
I wasn’t disappointed. I can still remember when I bought the print book (now at least 5 years ago). And I actually read it.
Did you know that Young’s grammar is available for Logos Bible Software? And it isn’t in any of the base packages, not even Portfolio? And that at $29.99, it is one of the more reasonably-priced intermediate Greek grammars that you can get for Logos?
Young’s is a winner for me. Maybe it’ll help you too.