Skippa,
I am not UK based so won't advise on a specific charity but I think you need to ask more pertinent questions.
These are for example the questions I would ask :
Which charity supports research into biomarkers, biological causes etc.
Which charities denounce the PACE trial and any further research into this model.
How much, if any, do charities pay their staff.
Which charities are fully transparent in what they do.
Ask yourself what's important for you and then choose the charity based on those specifics.
I think these are good questions.
Although I'm UK-based, I often give to overseas charities if they're doing projects I find particularly impressive (to END ME/CFS, for example, and the Lipkin/Columbia work). Worth bearing in mind that if you pay tax, that's less tax-efficient, though, because UK taxpayers can get Gift Aid added to a UK donation.
I donate on the first of every month and just look around to see what seems most worthwhile on the day, and give what I can afford for that month.
I've also given to the Forgotten Plague and Canary in a Coalmine documentaries, because even though they're not biomedical research, they're outreach that will, in the long run, pull in more money for biomedical research. They have the potential to reach not just non-PWME, but PWME who aren't in the community network yet, which is very important. And I think #MEAction is very worthy of support. We've needed a mass-advocacy platform for years, and suddenly we can reach 10,000 patients and supporters (and potential biomedical research donors) at the flick of a switch.