A Fair-Rite larger mix 43 core suitable for high power EFHW when stacked or as a high-power common mode choke.
 
If you are looking for a high-power end fed half wave antennas for 160m-40m this is the go-to core.  Stack 3 cores for 1kw.
 
This core is also suitable for use in high power radio amateur common mode chokes.  Used with Teflon coax like RG142 you will be ok at legal UK limits.
 
If you are looking for a very broad band non-reactive choke use in conjunction with Mix 52 cores and Mix 75 for the higher HF bands and AM bands.