Below are my reasons.
1. INTERNET SPEED AND DOWNLOADING SPEED: Airtel network has a very fast internet connection and downloading speed. Downloading speed of 112-200kbps for edge 500kbps to 10.0mbps or more for 3G or HSPA.
For instance, there were some files that I tried to download with one other internet provider in Nigeria that took me several hours compared to airtel that took me just few minutes to download it.
2. AIRTEL BIS: Airtel BIS is one of the cheapest in Nigeria. As low as N1200 (blackberry social) per month. Ranging from monthly. Weekly and daily subscription. Most importantly, Airtel BIS can be used on other non blackberry smartphones.
For complete monthly 30 days N1400, Dial *440*1# or send bcm to 440.
For weekly 7 days N400, Dial *440*2# or bcw to 440.
For daily 24hrs N100, Dail *440*3# bcd.
Blackberry social monthly N1200, Dial *440*4# or bsm to 440.
3. FREE DATA: Airtel gives 10mb data weekly if you recharge up to N200, also you get 1mb data daily by dialing *141*13*1#
4. Airtel has a "Gift data" platform where you can transfer data to friends and loved ones by dialing *141*1# and follow the prompt.