In my (oft-humbled) opinion, it doesn't matter what we use (or if we use anything) so long as we're reading the Word of God. I also don't think God puts a time or verse requirement on us. He just wants us to spend time with Him. To have a relationship.
Right now, I'm reading "Bad Girls of the Bible and What We Can Learn from Them" by Liz Curtis Higgs.
I'm only part-way into the book, but so far, I'm really enjoying it. There are also other books in the same series including "Slightly Bad Girls of the Bible: Flawed Women Loved by a Flawless God" and "Really Bad Girls of the Bible: More Lessons from Less-Than-Perfect Women". They also have workbooks that correspond to each of the books. Based on the first book, I'm looking forward to reading the rest of the series as well.
My girls have been working in the God & Me Devotional series for quite awhile. Both of them as well as my son asked for new devotionals for Christmas. How can a mom say no to a request like that? (She can't.)
We're getting our son one of the first boy's devotionals in the "God & Me" series. I'm really excited, though, about what we're getting the girls. We found them a devotional that goes in-depth into the book of Proverbs and applies the book to the lives of tween & pre-teen girls. PERFECT! This sounds like something they'll BOTH love...and something that will really help develop their character and as they grow into young ladies.
The devotional is called "Between God and Me: A Journey through Proverbs".
If you're interested, you can actually read parts of all of the books I've listed above on Amazon. (If you click on the links I provided above and then purchase the books after clicking on those links then I will get affiliate credit for your doing so. However, the links are provided for your convenience and you should feel no obligation to purchase through those links. While I do purchase many items (and some books) Amazon, I utilize Half.com or Paperbackswap for most of my book purchases.)
I pray you have a very Merry Christmas!