Hercules is spot on.
It's not working or being at home which defines how 'good' a parent is. You can be a brilliant working parent or a brilliant SAHP, or a rubbish working parent or a rubbish SAHP. God knows, there are plenty of neglected ( and I'm talking emotionally and physically) kids in homes where there is a parent or even both parents around all day..
The point is: the vast majority of parents, ie the ones who aren't neglectful or abusive or inadequate, put their children first. They prioritise their children over everything else, but don't need to 'prove ' this by giving up work.
If it were the case that children of working parents grew up to be emotionally scarred, unable to form positive relationship, less likely to do well educationally or in the workplace, then there would be evidence that having a working parent is harmful. But there isn't.
And before anyone starts citing biddulph, or such crap: for every view which claims to show that childcare is 'bad' , there is another view which shows the opposite!
Working mums have been around a while now as the norm. My colleagues in their fifties who worked while their kids were tiny- those kids are now adults with their own successful careers and lives
Which is perhaps the nub of the issue for the OP. If she feels that she's making some huge sacrifice by being a SAHM she's perhaps looking for some payback by wanting her own children to do better at school, get better jobs or have closer relationships with her when they are older , than the children of working mums. She stands to be very disappointed if this is her agenda. Stay at home if you want to, because its your preferred choice, and that should be 'pay back' enough. Your children will be fine either way, if they have loving supportive parents