I lived in Singapore for 10 years. I found that mesh jackets worked best, but I also used a Hein Gericke Air jacket: not mesh, better protection, but very good ventilation. I preferred it to mesh, except in heavy traffic. I also had Clover pants which had some panels in mesh, and liked it a lot.
To stay dry in an equatorial rainstorm, nothing beats RS Taichi Drymaster rain gear. It is made of a high-tech, lightweight material which keeps the rain out, but it is breathable and won't leave you sweating like a pig within minutes.