It's kind of like asking: What's better, cats or dogs? You'll get a different answer from different people.
For some people, tweaking is a way of life and a fun hobby. It's strips the phone of all the carrier-installed garbage and allows you to customize your phone to your exact liking.
For others, stock is king. But you likely won't find too many of those people here since most of us on this forum are here because we like to tweak.
As far as glitches is concerned, it's not as bad as you think. Remember, for every one person who posts about some kind of glitch or problem, there's likely 10 more who have had no issues at all and haven't posted anything because they have no problems in the first place. People tend to speak up more when they have a problem than they do when things are going well.
My advice: Flash to a custom ROM and take it for a test drive. If you don't like, you can always go back to the stock ROM and re-lock your phone. No harm, no foul. You really have nothing to lose by just trying it out
EDIT: ...and the answer is dogs
