The best replacement for netflow is sflow.

The best alternatives to netflow are rated as following:
★★★★★  sflow
★★★★  snmp
★★★  ipfix
★★  nbar
★★  rmon
★★  span
★  wireshark
★  flexible netflow
★  openflow
★  syslog
★  netflow lite
★  ip accounting
★  pcap
★  packet capture

Your alternative for netflow is not listed? Suggest!
Speaking about netflow, one probably shouldn't forget about ntop.

Other search terms related to netflow and their ratings are:
★★★★★ ntop
★★★★★ nagios
★★ nbar
★★ splunk
★★ solarwinds
★ prtg
You have in mind a companion for netflow and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of netflow in all years. Click on graph for more.
netflow
sflow
snmp