Disclaimer: I work for PingCAP. That benchmark didn't compare to TiKV. We generally avoid making such comparisions not because our competitors are better but because we know we will always have difficulty fairly benchmarking. Instead we generally do what is shown in that blog post: note in what aspect of a banchmark other databases are showing strength: because that indicates an opportunity to learn.
We don't view ourselves in competition with FoundationDB because most TiKV users want the ability to use TiDB with TiKV for SQL (and MySQL compatibility). If you know you don't ever need that then FDB can be a good choice (but TiKV can be as well).