So here is my...
Top 10 Finished Series I Haven't Finished Yet (and Why)
10. The Baroque Cycle by Neal Stephenson
I want to want to finish the The Baroque Cycle, but reading Seveneves and re-reading Snow Crash has burned me out on Stephenson for a long time, and The Baroque Cycle is not something to go into half-hearted. One day.
9. The Culture by Iain M Banks
I've only read the first book, Consider Phlebas, but I loved it. I fully intend, one day, to move forward and read the other books as I've heard very good things about them, and they are mostly standalone.
8. The Mistborn Trilogy by Brandon Sanderson
I read the first two books in a row and then came to a screeching halt at the third. The Final Empire is possibly one of my favorite books ever. I especially like how satisfying the ending is, but I didn't get that same satisfaction from the The Well of Ascension and so I lost momentum. Now I'm at a point where I would need to reread the first two going into the third, so it's a bigger commitment than just picking up one more book.
7. Gormenghast by Mervyn Peake
I first read Mervyn Peake in a small paperback, The Inner Landscape, that collected The Boy In Darkness with a short story by JG Ballard and one by Brian Aldiss. That little book started off what may turn out to be a real love of JG Ballard, but this entry is about Mervyn Peak. The Boy In Darkness is so perfectly creepy and weird that I had to track down more from Peake. Titus Groan continued that amazing creepiness but is very heavy reading. I just haven't been in the place to dive into that ocean again.
6. Locke & Key by Joe Hill and Gabriel Rodriguez
I have read all but the last volume. The problem was that the last two volumes were only out in hardback when I was reading the series and I just haven't circled back. I 100% intend to finish this series once I have the time to reread the first four volumes.
5. Alex + Ada
I have read this in single issues right up to the last issue. I think I've been putting this off because if I read the last issue it's really over.
4. The Elemental Apocalypse Quartet by JG Ballard
This is a loose quartet that is linked thematically and probably wasn't written as a series. But I'm including it anyway because after reading a lot of JG Ballard's early short stories and The Drowned World I need to get around to reading The Wind from Nowhere, The Drought, and The Crystal World.
3. The Keys to the Kingdom by Garth Nix
I've read all but the last book, Lord Sunday. I just ran out of momentum with this series, not because of the book themselves, just because I was listening to them all in a row. My husband and I are reading this series intermittently out loud at night, so we'll get there eventually. I am pretty curious about how it all ends.
2. Discworld by Terry Pratchett
What can I even say about Discworld that hasn't been said? It's amazing so far and I will one day get through all of them. But there are a lot, so I'd be willing to bet that there are quite a few people for whom this is an unfinished finished series.
1. The Uplift Saga by David Brin
The Uplift Saga is the #1 finished series that I have't finished because it is the one that I most feel I should finish. The Uplift War is right up my alley for scifi and is, if the internet is to be believed, the best of the three books. I enjoyed both of the previous books, so why haven't I gotten to this one yet? Good question.