Another major upside to using Kinesis is how seamlessly it integrates with AWS based consumers such as S3/DynamoDB etc. On the technical side of things, for Kinesis "each shard can support up to 5 transactions per second for reads, up to a maximum total data read rate of 2 MB per second and up to 1,000 records per second for writes, up to a maximum total data write rate of 1 MB per second (including partition keys)" (from AWS documentation), i'm not sure if a hard limit exists for Kafka. W.r.t stream ordering kafka preserves ordering of messages within the same shard i guess which Kinesis also preserves. Again authentication is made easier with the rest of AWS provisioning (IAM) so that's easier to build into Kinesis based application.

I think the bottom line is if you've other AWS components and are willing to be less hands-on about tuning with ease of setup and scalability, Kinesis is your best option. Else go with Kafka