BOG first and foremost.
CRT next, as it has gotten slightly easier now that BOG is open.
(There used to be a mad rush for Le Cellier Dinner that would have been second... but that has been downgraded a lot since they turned Le Cellier into a Signature option.)
If HDDR is on your list, it's next.
Signature - California Grill.
Ohana Dinner and Chef Mickey's after that, if either of those are on your list.
Ohana Breakfast is slightly easier to find, but if that one's on the list then I'd put it next. Crystal Palace Breakfast and Akershus Breakfast too.
Signatures - Narcoossee's, Citricos, Jiko. Sometimes Flying Fish can also belong here, it seems to wax and wane in difficulty.
Anything else inside Magic Kingdom, especially if it's going to be an EMH day (early or late). This includes lunch or dinner at Crystal Palace, or either meal at LTT or Tony's.
After that, you shouldn't have any problems at 180 days.
There are so many options at Epcot that it's fairly easy to get an ADR at any of those even within weeks of travel. Le Cellier included.
There are rarely problems with availability at anyting inside DHS or AK so far out... there are fewer restaraurants in these parks, but there are also fewer people who spend whole days in these parks, and so less demand overall.
Resort locations generally have availability until much closer to travel, and some will never fill up. There used to be a mad rush for Boma, but in the last year or so I have never had a problem getting Boma for anyone who wanted it, so I don't count it as a priority anymore.