I'd advise you to connect to fiber if there's fiber in Thika, either Safaricom or JTL Faiba, but Safaricom is cheaper than Faiba. Also don't know if Liquid telecom's Hai-Waya is in Thika but you can contact them on social media, it's a much cheaper option.
Alternatively, I use Airtel Postpaid unlimited since there's no fiber to home connection where I live. The Airtel network is good in my area and during downtimes I chat with customer care and they resolve the issues as quick as they can. Network issues may take like a week to resolve but it's worth it. It's 3599 per month.
Also note that the service is a one year contractual agreement with Airtel and since its postpaid there's also a deposit you will pay. There's also a complementary MiFi router that you'll be given which can connect up to 10 devices, so no need to worry bout the modem
This is my speedtest at the time of this post, the sim card is on my phone
This is my balance., the balance is set high to levels you cant really consume in 30 days
This is the notification of an issue i raised with them about the network in my area where for a while internet speeds were really slow. Expected resolution date was 10th June and they solved it yesterday 8th June