Broadly four:
Your Korean bank's own remittance service. Reliable, integrated with your account, generally the slowest and often not the cheapest. Good for large amounts where you want a clean paper trail.
Dedicated remittance operators licensed in Korea. Several operate specifically for the foreign-worker market. Usually cheaper and faster than banks. Check they are actually licensed — the Financial Supervisory Service maintains the list.
International money transfer services. The familiar global names operate here. Convenient, coverage into Kenya is good, cost varies.
Mobile-money-linked services. Some routes deliver directly to M-Pesa. For household support this is often the most useful endpoint, since the money arrives where it is actually spent.
Which is best genuinely depends on amount, urgency, and where it needs to land. Nobody wins on all three.