Hi @AbrahamYezioro - thanks for the kind words. 
I canât actually comment on what the âbestâ future scenario generator is as I donât have experience on these. Itâs probably not a very satisfying answer but I would only say that it would depend on your usage, as I like to quote - âall models are wrong, but some are usefulâ.
In general, I understand the idea is that the changing climate will have effects of shifting and flattening the distribution of some parameters. We can see this from historical data as shown below:
I understand these generators use CMIP models to estimate the magnitude of âshiftâ and âflatteningâ that they can apply to the present weather data and I think thatâs more or less reasonable way to do it. One recommendation that I made in the past was to make sure an up-to-date EPW file is used, as some older TMY3 files include data from 1960s and 1970s, to avoid âgarbage-in garbage-outâ type of situation.
Another part of these is that this type âshiftâ is not suitable for predicting extreme weather situations that weâre starting to see - the floods & wild fires for instance, although I would imagine them to be less relevant for the building energy simulation community.
Just my two cents.