I would say play the stock game for awhile and see if you like it, but be prepared that lots of strange gameplay behaviors will happen like torpedos running in circles etc. Your computer is performant enough for this game, hey it's a 2010 game...
If soon or late you want to mod it, then you have only the 1 reasonable choice which is TWoS, however it's oriented towards hardcore players which are used to play in high difficulty and high realism settings, nothing for the casual gamer I would say. I'm woking for longer on a megamod compilation which has 3 difficulty levels, also based on TWoS but it's not released yet...
In any case if you mod the game you must...
1) have version 1.2.0,
2) you must apply the U-Play fix,
3) then apply the "TDW Generic Patcher" before installing your own modlist.
If you install TWoS you can skip point 3), it will do it for you, but read install instructions carefully.
Enjoy the game, greetings.
XS