I would think the narrowbody and international time would be attractive to US majors. A few things to consider...

- Have you lived and worked much in the US (in ANY sort of job)? If so, the US airlines would probably view you as an american who happens to hold panamanian citizenship. If you have served in the US military, that would be great. If you have lived and worked mostly in Panama, then some folks might wonder if you would experience a big cultural shift in the US.

- One advantage to a US regional would be that you would meet folks who could later help you network into a major airline job. You may not make many connections like that in Panama.

- What happens if you don't get hired by a US Major? Where would you rather end up? US Rregional or Copa?