M1 has a ton of range and moderate speed but uses sharpened wooden poles instead of actual explosive warheads since they were originally used by Jap. whailing ships.
M3 on the other hand have explosive warheads (that usually oneshot everything below CA) and moderate range but are VERY slow. Their range allows long range torping but you will usually get into BB range with them so better have good engies when using them.
M2 is used only for the lulz when doing a fictory rush (and can be hilariously effective when it comes to murdering BBs if you get close enough).