I haven't read everyone elses response. I'll just tell you what has worked for me.
I read three versions, one of which is a study bible. I do not read the NIV because I don't find it a reliable source for various reasons. I don't like the other bibles that put everything in layman's terms because again, it's just someones interpretation and not necessarily correct.
I read the KJV, NKJV, and ESV. My husband and I share the NKJV Holman Study Bible and enjoy it for quick reference, but sometimes the interpretations are not as clear or even correct (IMO and from other sources), but it is still a solid study bible that I highly recommend unless you want to purchase commentary books.
I've been reading the bible regularly for two years and have yet to mark my bible as well, and let me just say that I regret it greatly. There are so many scriptures I want to go back on and I have forgotten where they are exactly. Perhaps I remember the book, but not the chapter/verse. I highly recommend writing in your bible, plus using a notebook for notes.