But if the choke balun is highly inductive and not very resistive, it will form a resonant circuit with the antenna's total capacitance to ground, and other reactances in the antenna/feedline/ground circuit. If this resonance happens to fall near your operating frequency, the balun will make matters worse then they are without a balun!
For that reason many authors suggest to use lossy core materials, including authors already mentioned in this thread. Ferrite has a complex permeability. At low frequency it's almost purely inductive, while at higher frequencies it becomes increasingly resistive. For that reason, at a sufficiently high frequency for the material chosen, a choke balun will oppose little inductance, but a lot of resistance to any common-mode current. This makes it work very well as a balun, without any risk for the mentioned resonances in that frequency range. But its resistance must be high enough to keep the loss negligible, or at least acceptable.
This comes down to selecting a core material that has a mostly resistive permeability all over the intended operating frequency range, and winding enough turns on it to keep the flux density at a level at which the loss in the core is low. At the same time there shouldn't be so many turns that inter-turn capacitance becomes a problem.
I have found the NanoVNA to be a great tool for measuring the characteristics of ferrite cores! You can take an unknown core, wind one or two turns of wire on it, or several if it's a small core, hook it up to the NanoVNA, and see the resulting series RLC graph over the desired frequency range. This gives you an instant idea of the core material's inductive and resistive permeability curves! By comparing to various manufacturer-provided data, you can make a good guess which material your core is made from.
