2D is ofcorse easier to do than 3D stuff.
Also the genres you mentioned are way too hardcore for the beginning. You need to get used to the basic concepts of game programming. A gameloop, input, drawing of graphics (and their drawing order), animation, timing, sound and ofcorse logic.
Pick a small project first wich covers all of these aspects. A puzzle game is perfect for the beginning. You have everything there you need... but the most important factor is that you don't need that
much media for doing such a game.
"What a puzzle game? I hate puzzles!", I hear you say. Well... I'm not really a fan of that sterotypic puzzle games, too. However there are nice puzzle games... so called "logic mazes" like "Mummy Maze" (over at popcap.com) it's based upon
"Theseus and the Minotaur" and I really enjoyed it. Or "Four Rivers" (Shisen) it's a Mahjongg variation. I really like that game therefore I made a speed version of it called "TinyRivers" (you can find it in "Your Games Here" somewere).
Once you are done you'll see tons of things wich you could have solved better and that's the whole point; getting skill. Your first game will just suck... as everyone's first game, but that doesn't matter as long as you've learned something on your way.
Btw welcome to JGO