I've been doing 3D programming as a hobby for quite some time, and I also chose to use OpenGL because it's not tied to any MS platform, and I found it somewhat easier to pick up than DirectX. While the online tutorials were useful, I'd suggest investing in a book that covers game programming more thoroughly, such as "OpenGL Game Programming", and also check out the forums on opengl.org and gamedev.net if you get stuck on some problem and need help. My first engine was based around Quake3 model format, because the documentation for it was easier to find than other formats. But to really learn game programming, you need to start out with small, simple things and work your way up from there. If you dive right away into a game engine, it's easy to get overwhelmed if you don't understand how it works.