Sorry to say but Jakarta can be an awful place to go as a casual visitor. The traffic is a mess at all hours of the day.
It is dirty and is woefully mismanaged on every level.
KL is a bit more sedate (fewer people live there)and a bit more planned, with a more modern infrastructure. If you are not going for business reasons I would choose KUL over CGK anytime. Also the food is better in KUL

!