There are a number of factors in internet selection and procurement including:
Speed vs Guaranteed speed
Some ISP's are overcrowded.
Different services offer different guaranteed speeds.
Not every ISP is good in every physical location (according to media)
Reliability, including ISP Choice, Media and Backup Media
ADSL is great for home, but not always for business
G.SHDSL is more reliable and Leased line tends to be the most reliable.
Backup links can be implemented such as Leased line with ADSL backup to ensure internet service continuity
Time for installation + activation
Some ISP's take 2 weeks, others take a week etc.
Hosting Access for Email/VPN or other services, including Dynamic IP vs Fixed IP
If you wish to have access to your files or email from outside your office then you will need a Fixed IP.
Many ISPs will renew your contract at the same price, even though year on year their cost prices come down.
Let us help you to find the right ISP, with the right package. We can negotiate as an IT company and get you a lower price without any affect to service.