Almost 14 months after submission the associate editor informed me they still did not start with the review process
Unfortunately, these things happen, and it sounds like the journal is at least being appropriately apologetic.

If you go do a different journal, you'll be starting all over again.  If this is a good journal for your field, and you think it's an honest mistake, then I would instead recommend asking for an expedited review process.  Since the editors are acknowledging they messed things up, you are likely to get faster and better consideration from them than another equivalent peer journal.

So: be collegial and gracious about their mistake, and next time you'll have good reason for when you send an earlier status query.