There are several different types of delivery companies in Singapore, and even among each type, there are some which specializes in a very niche type of delivery services in Singapore.
Firstly, there are companies which deal with postal deliveries. However, the most famous of which is SingPost, which is also the state postal services company in Singapore. They deal with regular letter and postal deliveries.
Secondly, there are companies which provide logistics support. Usually, these are private or public companies which offer warehousing as well as transportation of goods using heavy vehicles. If you need to move pianos, furniture, and anything heavy, these are the companies you go to as they own large trucks and specialize in such deliveries.
Thirdly, there are private or public courier companies. These are either locally owned such as Regent and Network Courier or they can be international public companies like Fedex and DHL. I like this group of companies the most because there are so many sub-divisions and operations within this niche.
Within the courier companies, there are those which specialize in international freight and delivery services like the most famous Fedex. These are companies which bring in goods from overseas into Singapore and deliver it to their customers. If you need something to be delivered cheaply overseas into Singapore, then such companies are your best choices.
Within courier companies, there are those which specialize in local deliveries in Singapore. Some of these companies like Regent provide mainly van delivery services only, while others like www.pcamasters.com are more versatile in that they offer delivery for both documents as well as parcels and are hence cheaper. (Companies in Singapore usually charge more if you use a van to get your item(s) delivered.)
Singapore has many different types of logistics companies, and therefore, you should look for the right type of delivery company and not blindly attach yourself to the first one you see. Make sure that the services they offer best suits your requirements.