(My first post on this forum... I used to post to the Dexterity forums a lot but took a break from Game Dev stuff and am now slowly getting back into it.. so joining this Forum is probably a good start!)
I'd say the best choice of genre to go for would be a combination of:
- The one you enjoy and feel most passionately about yourself!
- The one that is popular right now and is likely to give you good sales and rewards for your time.
- The one that is within your development time frame (maybe you only have 2 months or 2 years to work on it?) So that could be a simple Action Puzzle or a Massively Multiplayer Online game?
- Most important for "solo" Indie game devs is a game that is within your graphical/artistic powers. If you have the programming skills to do an Age of Empires killer, do you also have the ability to provide graphics for it?
- Same as above.. do you have the skills that are needed for the particular genre (online games need networking skills etc.)
- Avoid genres that are far too saturated, for example mahjongg puzzles ( ) or Solitaire card games.
Point number 1 is most important unless (like me) you enjoy discovering new genres and enjoy researching what's been done and what hasn't yet been done and (truly) improving on past developments. This is like a developers view of development rather than a true gamers view.
Can't really add any more to this without really understanding the meaning behind your question. However, it's been a fun way of braking in my first post and a good way of avoiding doing any "real work" myself