More Mausers and Lee Enfields made than K31ever, options and choices are much wider with them.
Mausers in many countries and calibers.
Lee Enfields also in many countries but in 303 only, with India manufactured and sniper versions in 7.62.
Three different action characteristics. All are sufficiently accurate and dependable.
K31 not used in war. The other two used in many conflicts all over the world, thus more to talk about.
Buy the first one you find in good condition at a good price, then go for the next one, etc. My preference is Lee Enfield.