I love the David's Tea advent calendar.
Disney did one last year with a book for every day, but the store lost my order, and then I wasn't able to find one anywhere else.
We always get the cheap chocolate ones that are $1 with a little chocolate for each day. For a while I was buying the Lego ones, but they're so expensive, and the girls have a lot of Lego now. Last year after Christmas I picked up a 2018 Lego Friends, a Playmobil Hockey one, and a Barbie one all for 75% off. I'm going to use those for the girls this year.
Last year DD6 was obsessed with Hatchimals, so I paid the money to get one. She was so happy and played with it so much that I didn't mind paying full price. They already have this year's out, and they've changed it to only 12 days. I know she really wants it, but I'm hoping to find it on sale in December.
I have advent calendars with wooden drawers I've filled other years if there were things my daughters were interested in that I could make up a calendar for them.
I also have a tree with little knit hats, mittens, and socks for each day. DH usually fills it with Lindt chocolates for me, though last year DD6 emptied it out while I was sleeping and had herself a delicious midnight snack.
One that was a huge hit with my girls was the Crayola advent calendar with a craft for each day. I saw them on clearance for $6 last year, and I'm kicking myself for not picking one up for each of the girls. They're $25 now.