The almost best results I had so far were with relatively thick solid copper wire. 82mm long and 1,5mm in diameter, that’s what’s usually used for main current (230v). That was for diy nodes. The semtech node with the pcb antenna performs far better, but it works directional. So you’ve got a huge range looking ahead while you’ve got a much smaller range in the other directions.
This solid wire works far better than a helical antenna.