I've been using Poslaju and Skynet for the past 5years for 30-50 parcels every months.

Poslaju
* Delivery every place in Malaysia, best for kampung/P O Box address
* Cheap rate, fast delivery
x Always run out of flyers/plastic
x Very strict on the packing - wrap, tie, no loose item inside
x Single parcel for single address
x Have to que in counter (this is my main concern, waste a lot of time)
x Always crowded with no parking space
x Expensive for heavier parcel >3kg
x VERY Slow process time except Poslaju counter
x Online tracking fail 80% of the time

Skynet
* Good counter service - no que, help to pack, just sit down and wait
* Flyers available most of the time
* Packing in any form as you like, as long you feel safe
* Multiple parcel single address
* Cheaper if >3kg comparing Poslaju
* Even cheaper if you get offer rate from the branch manager (my rate: 1st KG RM4.50, add KG RM1)
* Good online tracking status

I used Poslaju for the first 2-3years just because of its rate.
Later on I found a Skynet branch offering superb rate for internet trader, no more Poslaju for me.

However both have good record over the 5years, no missing parcel, only happen once the Poslaju counter aunty act very slow and blur and accidenly exchange the address of my 2 parcels, which I've write clearly the correct address on the box itself, end up 2customers received wrong parcel and I have to ask them to post to each other.

they charge by each shipment/address
better u use registered post or pos ekspres standard envelop ~RM2.50