The two books provide different sorts of information, so use them both for best results. The number of books issued usually does not tell us much about the financial stability of the publishers, just that the publisher is set up to handle a certain number of books. Smaller and medium-sized publishers often have excellent reputations and good relations with authors, but may still be a poor place to submit a particular book because of its subject matter. Try to find books like yours, and note who published them. The library, if books are kept up to date, is an inexpensive place to research.
Bookstores are a good place to look, because they show current books.
If the book is too much like the one you have and was published in the last two years, the publisher may not be interested in another book like that so soon after the first one. Ideally, look for a publisher who publishes books in your niche but lacks a book on your particular subject. Make notes about the book and publisher, read up on the company in LMP and Writers Market for a better picture. Always check the Acknowledgments page in good prospects, as authors almost invariably thank their editors and agents. It's a good idea to call the publisher to find out if that editor is still at that house, as people move around often in the publishing business.