On the whole, let them have it for free, unless you can think of a better use for them.
I buy logs in bulk for my wood burning stove. I pay around £175 for a cubic metre delivered on a pallet.
From these people, if you are interested:
https://www.buyfirewooddirect.co.uk/1-25M-crate-kiln-dried-mixed-hardwood-firewood
However, those are cut to length (around 25cm), then split. They are also kiln dried down to a moisture content of 20% and finally packed onto the pallet, which is weather-proofed.
So the commercial value is a lot less than £175/cubic metre
If he wants to use them in a wood burner, then he should really cut to length and then split the logs and then leave them in an outdoor, but sheltered location for a couple of years to dry out. A just-felled tree will be full of moisture, and that will make the wood unsuitable for burning for a number of reasons
1. the heat output will be lower, as some of the heat energy is being used to heat and evaporate the water within the logs
2. the water and resins will condense onto his chimney walls as grime and soot, increasing the likelihood of a chimney fire
3. It's a bit anti-social, as there will be a lot more smoke coming off the woodburner
Finally, of course, it's up to you, but if you would have to pay to have the stuff removed, then why not just let next-door have it for free?