I'm not an expert (my closest experience with dyslexia is as a teacher, and none of my students needed accommodations for it), but one of the things that is useful for dyslexia is to try and provide orientation in some way. One thing that a lot of people don't realize is that the fonts and typefaces they are using do not fit the purpose, and shoddy design is contributing to woes of the dyslexic as well.
OpenDyslexic seems to me to be an obvious choice due to its license, but one of the concerns that I have with it is that the change in weighting feels very unnatural compared to other text. One conventional wisdom for text is that you want your font to be as light (e.g. thin in stroke) as you can get. Dyslexie is certainly more readable for me, in part because I think its weighting is lighter (and the shift in weighting less extreme) in general.
Lexie Readable seems like another option, though it's pretty subtle.
https://www.k-type.com/fonts/lexie-readable/
Apparently Comic Sans is popular as well, which has given me a small appreciation for it.
There is still no justification for the existence of Comic Sans in this day and age. :D
I also think Dyslexie is more readable for me as a non-dyslexic. I would like to know what dyslexics think. When I work on library posts for facebook featuring text in an image, I find myself choosing my fonts carefully for legibility, and many are just plain awful for any practical use. I hate Helvetica and especially its clones on a gut level, but they are generally quite readable.