New here- advice on game genre

[crocodile]

Hi everybody, I'm quiet new to the videogames world. I don't have really many hours to play but I'm fascinated by realistic sims, not commercial game like online FPS, sports game etc. The problem is that I can't decide with what sim genre to start with. I know that this forum is mainly for naval enthusiastics, but I noticed that many of you also play flight sims and other sims, so I wanted to ask you few question just to have different opinions.
I'm not scared by large manuals to read and game complexity, I'd just like to find a genre and practice in that one, since I don't have many hours to make experiments and much money to buy several kind of games.
My PC at the moment is 5 years old. Game like DW, SH3 and perhaps SH4 can run, new flight sim no, but of course old flight sims should run as well.
What I'm mostly concerned about is possible bore I could find playing certain sims.
1)Submarines have a huge impact on me since I saw movies like Das Boot etc but I wonder: in WW2 subsim isn't getting a bit boring to hunt down ships convoy and never submarine vs submarine. Aren't this convoy attacks getting a bit boring in the long run? Can ships in SH series sink Subs with Torpedoes or only with deep charges?
2)And in modern sub sim like DW isn't getting a bit boring after a while tracking down sonar impulses, noises etc?
3)About combat flight sims: the battle in the sky are always different or after a while is always about getting behind the enemy tail in ww2 sims and learning to use avionics in modern sim?
4)A general overview question: what sort of battles are more exciting, various and with emphasis on tactical and strategical abilities rather than the technology your faction own? The ones in the skies or the ones at sea?
Thanks a lot for your help, I know that questions like this are difficult to answer but I just ask for your experience and would like to hear what actually made you like a sim "sector" rather than the other and what aspects keep you interested in a particular genre.