I wouldn't have wanted my mum, but not because I would care about her seeing my bits and pieces. She just wouldn't have been very helpful.
She went abroad to lend support to my sister, giving birth in another country, and from what I can gather, was not all that helpful in supporting her in standing up to the incorrect advice she was given by HCP about BF. (In fact, I put my DSis in touch with La Leche League, from a third country, which was more useful to her.)
To be honest, DH at the births was a bit of a PITA at times. He wasn't always madly helpful, and did things like putting a whole bottle of rescue remedy in my water, when I would have preferred them separate. Also, he wasn't very clued up on labour, so, for example, when I was pleased to be vomitting, as I knew this was part of transition, I was having to explain that to him, as he thought it was a worrying sign.
So, I would say you want someone who knows a reasonable amount about what is going on, and who will focus on you, and helping you, whoever that may be. And if it's not your mother, then that's fine. Labour is about you and the baby, not about her.