Wow! Willing to switch airlines over an issue caused by you, interesting.
It seems people always blames the airlines for their lost item THEY left behind.
In the airline bus. gate agents, F/A's, Pilots and evn cleaning crews and catering employees are way too busy to jump right away on top of your lost items.
If it was found by an airline employee I assure you it was turned into the proper authorities, and stored for future retrieval by the owner at a later date. Yes sometimes these things do take time to process and get through the system. However if not found by an airline employee, if plane was reloaded, and another flight taken place, then any joe blow could have retrieved lost item and kept it, or turned it into a different flight crew not knowing what flight it was lost on and possibly turned it in to lost and found in a different city than where you arrived to and will take much, much longer to figure it all out.
Sorry about your lost item(s). But to leave an airline because they cannot find it is just childish and juvenile. After all you as well as others are the ones that lost or left items behind and seem to always DEMAND that the airline jump thru hoops to find it and if they don't most tell the airline that they have to replace said item(s). Laughable, not going to happen.
Being a veteran of flying I would think you would have the means of obtaining insurance for items you travel with as well as insurance for other issues. If said item was bought on certain credit cards as well as your ticket, check with them as some provide flight insurance automatically as a benefit of using their cards.
I hope you are reunited with your items. And sorry but I am blunt. But to threaten to leave Delta over your very own actions that caused the item(s) to be lost is just ridiculous. Delta is and outstanding company and right now they are the no one of the legacy carriers. If you really want to leave them for one of the other two biggies, you go right ahead. The customer service at the others is way worse than at Delta. If it were me I would suck it up as a dumb move by myself, get over it and go buy another one. If this was a work related camera then maybe your co. had insurance on it. Either way I wish you the best luck, but it's not Delta's fault...