Sounds vary. What works well for accompaniment of English or modern "folk-alike" songs (I'd suggest an Army and Navy style) may differ from the rounder sound more suited to "celtic" (the guru of which is Hathway, very reasonably priced at about £700), or the "bark" that old timey and bluegrass players prefer (think model-A or F-style).

Sound is the most important thing. Trust your ears.

Intonation is sortable by a good tech - bridge location is easy to sort on most mandolins, with the aid of say a Petersen tuner. But there is a big but. If fret spacing is wrong (which is rare) that is unfixable, and if nut location is wrong that is hard to fix but nut adjustment sort of like Buzz Feiten can work. Saddle compensation may be more radical than you expect to need.

Action on a mandolin can usually be sorted at saddle or nut - but beware some mandolins do not have truss rods so if the neck progression is wrong it can be problematic.

Making a mandolin pluggable can be tricky - many stick-ons or undersaddles give too much body thump and although you'd expect to be able to get rid of it with eq'ing out everything under 300Hz it does not seem to work, so getting one that is factory pluggable may be a good move.

Oh, and avoid anything from Saga Musical Instruments of San Francisco like the plague - I have one of their Kentucky flatirons which came with a lifetime guarantee to the first retail purchaser (me!) and when the top cracked along its length they flatly refused to honour the guarantee because I was outside the USA. That sort oc cynical dishonesty should be discouraged.