Anecdotally for what its worth my personal preference to avoid gaming the system is to run iperf3 on a random VM that has a solid tier-1 network and many peering agreements. I start it on a non standard port non standard for iperf3 and test bi-directionally with TCP and UDP. On each end I use the "watch" command to call a simple bash function that sorts the output of "netstat -s" to get tcp retransmits. I also watch the output of "tc -s -p qdisc" on each end to see how many packets had to be reordered or dropped. This can be useful for tuning or picking traffic shaping methods.

In reference to gaming the system one can also run iperf3 on ports used by https, voip, common bittorrent and other service ports to see if the ISP is blindly traffic shaping on ports by means of different behavior per port.