"Worst" is subjective and a matter of opinion. And even if it may be a more widely held opinion, it's far from unanimous and each person has their own rank order of what would be worse working their way down the list and that can also vary from flight to flight and aircraft type to aircraft type for a GA to possibly even weight in on. The only thing would be for a GA to call people up and ask (or as you note, go make your preferences known to the GA). But there are so many (too many) factors for a GA to individually weigh in on what's a "worse" seat. 1A on the CRJ-900 and E-175 is a great seat. 1A is one of the best seats on the D1-configured 767-300 too. Conversely, the bulkhead row is pretty tight on aircraft like the 737-900 and 757-200/300 with domestic F seats. But again, what's "worse"? In most standard F cabins, I prefer a standard aisle over a bulkhead aisle but if I find myself in a window seat, I'm more apt to prefer the bulkhead window over a standard window seat in another row. Other factors on where I would prefer to sit include whether it's a meal flight. If I'm getting upgraded and it's a meal flight, I might be more apt for either being in the front or back depending on the sequence for meal ordering. Something else that would factor in is where I'm flying in to. For example, if I'm flying into DCA or out of HNL, I would prefer a window seat on the left side of the aircraft, even if that means taking what may otherwise be a less desirable seat based on other factors I usually consider.