You sound like a serious journal person, so I imagine you value the robustness of the app, as well as its ability to handle many journal entries or long entries. Active support from developers would also be valuable. For this reason I'd suggest looking at Scrivener or perhaps a general word processor like Nisus Writer Pro (not sure about the latter's tagging features).
Years ago I used MacJournal exclusively and was happy with it until the program crashed during a sync with my iOS device. Everything was lost, at least I thought so at first. I discovered that the program icon, which is really an application package, can be opened to reveal the components of the MacJournal program. One of those components is a folder with all of the text entries; the database with names and dates of the entries is another component. I was able to recover all the entries, but was unable to associate the entries with their title and date.
I've also tried using traditional word processors like Word, Nisus Writer and others. My issue with this approach is that these programs lack an integrated database like MacJournal, which keeps track of the entry title, its date and the tags. With a word processor you generate a folder with many individual files but no convenient way to organize them. I tried using document management solutions to tag and organize files from word processors--it works and may be worth trying for you, but it can be awkward.
Scrivener is a large and many-featured program for comprehensive handling and creation of large documents, which may be composed of many smaller documents, such as a journal. Scrivener has several features to associate tags, key words and notes/annotations to the journal entry.
Scrivener also has a built-in backup feature which in my experience works well.
An oddity about Scrivener is that when you want to produce a finished document, it is "compiled." By compiled, Scrivener means that the text of the document and the associated tags, notes, footnotes, etc. are integrated into one entity. The idea is that when the author finishes the document it is compiled into a one thing, usually for formatting by another program such as Microsoft Word (note that Scrivener does rich-text editing with a comprehensive and customizable editor).
Scrivener is also available in both Mac and Windows versions. Both are up-to-date and have similar functionality and appearance. The iOS app is awful, however. To the best of my knowledge the apps works but using it is awkward and not intuitive at all. Also, at this time the app only syncs via Dropbox.
Hope something here helps. Take it easy.
