Safaricom's prices are also good, but not for bandwidth less than 1 Mbps. And their support team seems to have come of age. Initially there were a lot of issues with support, but it seems that has been addressed.
My issue with AccessKenya are many, but the most frustrating one is not being able to access or admin my router. You can imagine investing on one of the most advanced Cisco routers and having AccessKenya change the admin password and there is nothing you can do about it? That does not cut for most IT or Network Admins.
But in the end, the choice comes down to you. As someone said, you can have reliable and cheap, there is always a compromise.