Suggestion screen size

[loffer]

Hi!

I have got an old rather small cabinet, that I plan to get a new monitor for. It is only 49cm width , 19,5”. My option for a LCD is 22” or to put a 32” vertically. Or do I have any other options maybe? Which is best for a MAME cabinet?

[BadMouth]

22" is perfect in one orientation or the other, but if mounted horizontally the vertical games will feel small and vice versa.  If the cabinet is small, then it might not feel too awkward.
If there is room for the 22" to rotate, that could be the best of both worlds but will require some configuration if you want the rotation automated. https://forum.arcadecontrols.com/index.php/board,51.0.html

If you are only running MAME the 32" mounted vertically would look nice for games of both orientations and will also display the bezel artwork, but you might run into issues getting other emulators that aren't as flexible to play nice.  I haven't gone this route, so do not know what all is involved outside of MAME. It is pretty straightforward to set MAME up to work with this.
Others have done this so hopefully they will chime in.

[loffer]

Thanks, I appreciate your input!

[mixlplex]

I've never tried it, so I'm posting this as caveat emptor (or whatever the appropriate phrase would be for something that's free) but there's this if you decide to run a vertical monitor: https://www.verticalarcade.com/

[javeryh]

I've got a 19.5" wide cabinet and I used a 17" 4:3 monitor in vertical orientation and it looks huge. I would definitely go 4:3 (or 3:4) and not 16:9.

[harri]

My option for a LCD is 22”

If that is a 16:9 then you could think of 20" 4:3 monitor. I don't think anyone makes them new anymore so you need to find it used. There are couple of modern monitors with odd aspect ratio like LG DualUp but I think that's slightly too wide for your cabinet.

[RandyT]

My current philosophy is to use a 4K monitor and fill the space you have with as much screen as possible.  Consider the screen in that space to be your "canvas", upon which you will be displaying the game.  The high resolution will allow for much flexibility by way of shaders or just appropriate sizing.  Just because you have the screen real estate available, that doesn't mean you need to use it all for every title.   As BadMouth stated, whatever you run will need to have similar graphical output flexibility to that which is available in MAME.

This also means, however, that you will want a decent system and a graphics card made within the last 10 years to drive the pixels.  If you are using a 90's era Celeron with on-board graphics, find a nice 4:3 which fits, mount it horizontally and deal with the smaller vertical games...unless that is what you play mostly, in which case the opposite orientation would obviously be better.  But this then becomes a niche build, as most other applications become size-limited by the orientation (if they support it at all).