The CSU system is great, and even with recent tuition increases is still an unbelievable bargain for CA residents. All of the CSUs are similar in price and prestige, so I'd say you should base your decision in large part on where you want to live for the time you are there. I went to SDSU, earned my BA and enjoyed it a lot. Nice city, lots of cool people, girls, parties, etc. as well as some really cool professors. Most important was that I enjoyed it.
A couple other things to consider are, since you want to get a computer science degree, I'd check into which schools have the best computer science programs as some campuses are more known for certain programs than others. For example, San Diego State (where I went) is known for its business program and psych department. Also, some of the CSUs are becoming increasingly impacted, especially in certain majors, which can make it difficult to get classes. For example, like I said SDSU is known for its business and psych programs, so all of those classes fill up very quickly and if you don't sign up ASAP you may end up having to wait a semester or take it at some weird time (like a night class). Also, in impacted majors, if you don't keep your GPA up you can get dropped from the program.
Anyways, bottom line is there are a lot of great options. Choose one that has a good computer science department and is somewhere you want to live.
Also, don't let all of these internet haters get you down about having a GED. If you graduate from a CSU with a high GPA and do well on the GMATs there will be plenty of schools that will take you, and they won't be asking about where you went to high school, especially if you have a lot of good real world experience. When I applied to law school there wasn't even a place on the application asking about high school... they'll look at GPA, GMAT scores, internships/work experience, personal stuff, not your high school diploma.
