I usually say 'aitch,' but if I'm spelling a word, I think after some letters 'haitch' sounds better. I can't think of which ones now, but I know I do sometimes say it like that.
Oh my god, I'm losing my mind. I've just sat here for like 5 minutes trying to figure out what the hell you were on about, then I read the first part of the title. >.<
I thought it was some sciency word.
Yeah, I'm gonna go sleep. Though for the record I say Haych =D