Your title says "The most modern and effective bolt action service rifle ever."
Your survey asks for "Your favourite bolt action service rifle."
For the survey, you have duplicated most answers while leaving many countries off the list. The Gewehr 98 and Karabiner 98a should probably be there as there will be some familiarity to many (would get votes from me). I own a few Mausers, as well as several Lee-Enfields, and Remington-Lees, and the M1903 Springfield. Obviously they all get my vote.
As far as the most effective bolt action service rifle ever, that title has to go to one adapted for the Japanese, by the Italians, that really wasn't that modern, practical, accurate, or even reliable, but was employed effectively against the highest level target ever. Built in 1940 in the Terni Arsenal, chambered for 6.5x52, was an ugly, short, bolt action rifle with the serial number C2766.
A simple Carcano M91/38.