but when is a regular drill better than a right angle drill?
Anytime you are not in a tight space.
I've got an 18v dewalt 90º, fantastic tool, I wouldn't give it up readily. I also don't particularly care for it as an everyday drill. That said, I did use it at work as an everyday drill for a couple years due to the mix of what I was working on, but generally, the right angle drill is more awkward to handle outside of tight areas.
A regular drill is a lot easier for one handed operation, especially overhead. Until you build up forearm strength, the 90º drill is going to be a wobbly ***** to hold steady. The long body can also be a hinderance in normal sitations when you as the operator are in a position that doesn't lend itself to clearing obstacles with the drill.
Alex.