There is a lady on another forum with daughters that 3c hair and one has 3a & 2 something and they have like tailbone length hair and she *loves* the QOD Max Organiq for them. She does only two passes (as do I when I've done that treatment) and that doesn't straighten their hair too much and it doesn't frizz in humidity. She does them every 4 months.
I say try the cyestine first since it's the least damaging of all for the hair. As a rule, when testing anything, I try the temporary stuff first,then
go for the permanent treatments.
Do plenty of reading and research and read customer reviews and you'll be fine!!!