I'm long-legged, 6'4" and travel with a legroom-hugging service dog. MCE will work reasonably well. I would not want to sit in a standard economy seat at your size, even for three hours.
Check the plane types scheduled to operate your flights. The A319 offers more legroom in the exit row - on these, row 14 is the place to be.
AAs A320s are especially bad - these are ex-US Airways planes and don't even have proper MCE (where AA removed rows of seats to create the cabin) - here, AA went and sells the bulkhead row and the exit rows as MCE. Row 11 is it on these. If you cannot snag a seat there, I'd select another routing...
All 737s have a 'proper' MCE cabin. Check if the plane scheduled to operate your flight offers inflight entertainment - if it does, get a window seat (window seats do not have a legroom-robbing equipment box) or the bulkhead row (8). Avoid the bulkhead on planes not offering inflight entertainment - much less legroom.

For details, see the seating threads over in the AA forum:
https://www.flyertalk.com/forum/amer...idated-32.html
https://www.flyertalk.com/forum/amer...interiors.html

some 'good' seats are reserved for elite status passengers, and only become available shortly before departure as upgrades clear. Check back on the seat map a few times in the last day prior to departure.