or even 1.4:1 ratioI don't do a whole lot of portraits but I prefer A format paper which is 2.8:1 ratio or, near as dammit, 3:2.
I no longer do proper maths.or even 1.4:1 ratio
As long as it suits the image it does not matter. But its size will rather depend on your printer or paper. No point in shooting fora size or format that you can not output. The same applies to frames and mounts. You need to be practical.
The classic 1:1 format is hard to beat.