STPM pros and cons.

Ranging from cheaper fees, you can choose and slowly decide on what to do next if you are in science stream, and the last 1 1/2 year of experience in STPM (last part of studying in school). Also, its quite recognised locally and overseas (public or private universities).

Cons? Like what others said, your school will be the problem. The teachers available etc will be the issue.

Still, don't jump into anything just yet. Since you are not close to knowing what you wanna do next, like what I told others, try STPM and get the grades in STPM then decide later. If you already have a clear plan, then you could just opt for A-levels/Foundation etc instead (only if you have the $$$ to do so).