Stuck between two projects

I want to be a published author. I recently finished a first draft of my book and sent it to an editor to be critiqued. While he was doing that I decided to work on another book, a stand-alone. Now my first book is about 100k words and is part of a series that I could wrap up in two books at the least. The other one is just barely over 10k words, and I'm not sure if I can even get past 60k as it's not meant to be some 100k epic fantasy like my other book. The editor came back with a report and now I have a couple weeks of work on my first book at least.

The problem is that do I work on the first book or the second? I've been told a stand-alone is better for debut authors, but my editor had a LOT of good things to say about my first and the second one won't even break 80k unless I artificially fill it out.