I am a childminder, so there may be some bias here, but I always think it's better for babies and very young toddlers to go to a childminder. Smaller groups, quieter environment and the ability to focus a little more individual attention on each child.
I think older toddlers can cope with the pace and structure of a nursery much better, but babies need something a little bit more like home. Especially if it's their first time being away from their mum.
That said, it's also up to how you feel about it. The best thing to do is go and look at some childminders and some nurseries and see how you feel about them. Some parents prefer nurseries, some parents prefer childminders. Unless you go and look, you'll never know. Ask around any friends you have with kids, and see if they recommend anywhere.
If you're having a problem with thinking someone might be his 'second mum' a nursery might be better for you. You could always do both, and send him to a childminder for a few months, until he's a little older and used to being away from you, then change to a nursery.
Some nurseries can be a bit inflexible with times, because they need to close and can't have kids and staff having around waiting for parents, whereas a childminder can be much more flexible. On the other hand, if a childminder is sick they might have to close at short notice, whereas a nursery might have staff to cover. (Same with hols!)
Good luck, I hope you find somewhere to suit you both!