[pickinthebanjo]

I own both, I prefer SH3 mainly because of the Atlantic theater but SH4 has that as well (Some mod I used in the past. I can't recall the name, it's common though) but also because I find SH4 to be troublesome. I like the plane attacks alot more in SH4 but thats about it, the american subs confuse the hell out of me (it's that damn hydrophone/SONAR and that TDC) but I also find it to be less stable than SH3.

SH3 has alot more mods available to choose from that include the sub interiors (Diesel room, Officers quarters/Mess, Crew quarters and the galley) as well as the new Merchant fleet mod, and many supermods that alter the game in many ways. The greaphics are fine by me, I sound SH4's to be chunky. (and the crew always stared at me, it was unnerving)

With mods like SH4 effects, GWX Enhanced Damage effects, and SH5 water you can get pretty much what your looking for but with more stability, immersion and realism.