All around in the last century goes to the K98. The action is still being used today in modern hunting rifles and associated derivatives. It's the most simplest and strongest action ever developed.
The best of both wars was the Enfield No4. Unmatched speed and magazine capacity, with better sight pictures and battlefield readiness than the Mauser K98. It didn't last after the war in major conflict usage.
If you gave me either one to go to war with today I'd pick the K98. It's simpler and parts availability is rampant.
There are plenty of rifles which are simplier than a K98k. Mosin Nagant, Arisaka (a simplified and improved Mauser itself), etc.
Strength of action really doesn't matter to much on the battlefield, as long as it can use the ammo it was designed for it doesn't make a difference if it can handle two to three times the pressure of that round as no one is using that pressure.
Plenty of bolt actions have strengths in different areas. Mosin Nagant is the ease of manufacture. Lee Enfield has speed. Mauser has a generic platform. Carcano has being the most average rifle ever issued, not really fantastic in anyway however reliable and easy to use, and certainly many steps above a Mosin Nagant. Arisakas are a better version of a Mauser, faster to shoot, tend to have better sights (especially in the later models) and pretty much all the other advantages a Mauser has. Austrian-Hungarian M95 have speed of reloading and are pretty fast to shoot. Austrian M88/90 has the same reload time as a M95 but a faster bolt (the action wears out significantly faster though). Hungarian M35s combine that quick reloading with a more traditional turnbolt design.
Then there are others, Mannlicher Schroders, Commission 88s, Mannlicher M93s and M95s (of the turn bolt variety). Lebels, and Berthiers. MAS 36, and Rosses. Even Krags. Overall they tend to be all fairly serviceable firearms, some were clearly outdated at certain points, but in there heyday they were all sufficient.
Personally my favourite to choose would be something like a M1904 Portuguese Mauser-Varquero, fast action, easy to strip bolt (once you understand how for my mechanical mind it is a thing of beauty), and light round. Otherwise I am quite attached to the Swiss Rifles, not much you can do to improve those.
These types of questions are like what type of food tastes best? The reality is everyone is going to have a different favourite for different reasons. Everything has pros and cons. The Lee Enfield for example has the risk of rimlock and requires more effort to produce and maintain.