With both FotRS-U & TMOv2.5 BH edition... both are good in their own right.
Fall, is a bit easier but it does have in it, workings to add in, that make it as realistic as the player wants to make it... as it regards torp's & the dud rate on them.
It does have as well, the Nipon Maru/Nihon Kaigun add in, for the IJN/merchie's addition. Then, there is vicker's work to add to it.
So, there is a lot to add in to the base segment of it.
As pointed out, TMO, being reworked by Bubblehead1980, to be able to actually be surfaced & attack targets... is a very big improvement, as is the more realistic ship traffic, the damages model... the ability to go with having torp's with tnt early on then having them with torpex.
Currently, BH is working on a more added to updated version, which will be released... soon as He feels it is ready... which, is a good thing.
I can only say... is try both & then roll with 1 set up... or the other... or heck, do both, if you have the space for it.
It's all... up to you, in the final end analysis...
Myself, I enjoy both...
Hope this helps... as always.
M. M.