my 2 cents based on experience:
i. KCB- Terrible. The bank has to send you a TAN via your phone line to access your acct and another TAN to make a transaction. You have ti receive the TAN within 2 minutes before it expires. Most of the time the TAN does not either come thru or the transactions fails to go thru;
ii. Coop. Gives a card kama ile ya KANU for any transaction. Unochomoa and then you check the codes as per online prompts. Looks archaic but works. I use it for Coop to Coop transactions only.
Looks like CBA is the way to go and i will try it too.
"Things that matter most must never be at the mercy of things that matter least." Goethe