tl;dr: Female class voices are generally better (and this is from a person who loves the male SW)
I disagree. With the exception of female Agent, I like all the male voices better in cases where I've heard enough of the female to judge. Can't stand female SW for example.
I can admit attachment may be coloring my perspective though. For example I initially tried to roll a male agent but once I realized everyone wanted to be Thrawn (inevitable in retrospect) I switched to female. While I didn't mind the male voice at the start, hearing it recently I found it too nasally and annoying. For me the voice is now the character, anything else sounds wrong.
Of course, anything is nasally and annoying if it's competing with Jo Wyatt, so there is that...
Well, since we've gotten on the topic of protagonist voices. Why don't we list our Top 5 favorite?
Go!
1. Male Knight (David Hayter baby!)
2. Female Agent (dat Jo Wyatt)
3. Male Inquisitor (perfect levels of snark mixed with Palpatine-style "something something dark side" spitting out of words.)
4. Male Smuggler (too funny to dislike)
5. Male Trooper (became a fan of Brian Bloom because I now associate his voice with Jackie Estacado from The Darkness 2. Ironic that it was a recast, which I usually hate)