There are quite some alternatives to Packet Tracer, each with its up- and downsides. The major downsides of alternatives is that they often require a lot more knowledge and work to get working, as well as the requirement of actual firmware of the networking equipment you want to run.
Here some alternatives:
GNS3 – I personally use this program as well. Setting it up is not too hard and has become easier in the last years, but it does require firmware.
EVE-NG