Without a doubt, I believe Accordance XII is the best. In fact, I was going to buy Logos 7, but due to their marketing and after more research, I bit the bullet and went with Accordance XII Koine Greek Expert.
If you don’t want to spend that much money (plus more for the Greek books included in Koine Greek Master that aren’t in Expert (to avoid buying Latin books)), one can download Logos 7 Basic, Verbum 7 Basic, Noet, and Logos 7 Academic Basic. Once all the apps—via your Faithlife account—sort out all the works that come with them, and your libraries indexed, you’ll have a lot to work with. Even more when you find relevant free books. From there you can build your library with books you actually want, instead of 4,000+ books you’ll never use.
And though I use Accordance, I do use “Logos 7 Basic/Verbum 7 Basic/Noet/Logos 7 Academic Basic” for books that Accordance, unfortunately, doesn’t have. But I must say, do not start using Bible software for Greek until you actually know Greek.
Any questions about which Greek books I have purchased from Faithlife I’ll gladly answer and would love to hear from anyone who uses any of the aforementioned Bible software programs.