Mash,
We have very few corporate internet providers, and if you rule out 2 of the biggest, you are remaining with either one or two others in Nairobi.Which leads me to think you have already made your choice, you are now just looking for some form of outside validation.
Without Liquid or Access (IS), you are left to deal with Safaricom, JTL and Orange (Telkom). As Wash said, contacts are on their respective websites. But it might all come down to which provider has infrastructure ready in your premises.
Zuku may also have some form of commercial offering, you can check them out.