This is such a personal-preference kind of question. My son goes to a daycare, where he started at 13 weeks. My sister has a nanny for her girls.
We made the choice for daycare for several reasons:
- Socialization opportunities
- Licensed and inspected providers
- Built-in activities and stimulation
- Not totally comfortable having a stranger in my house all day (my aunt and uncle had a nanny that took advantage of their hospitality and all of their utilities went through the roof. Come to find out she was doing all of her laundry including sheets/towels and all of her cooking at the house while they were at work)
Upsides:
- Strong social skills and interest in playing
- Stands up for himself
- Early talker and more advanced language b/c he's around "big kids"
- Provider has become like an aunt to him (family home daycare)
- The aides (college students) have become our date-night sitters
Downsides:
- lots of "colds" during the first year of daycare
- we have to be "on schedule" every day and out the door for drop-off
- she closes for vacation, so we have to take vacation when she does
- if he's a "little sick" one of us stays home. With a nanny, they will likely still come unless your child is running a high fever or has something serious
What I have noticed in my nieces:
- They are sweet, but they don't know how to play with other children b/c they don't have those opportunities
- Less "scheduled" b/c they don't have to be- sleep when they want, eat when they want, etc.
- Can't be left with anyone other than their nanny b/c they haven't figured out that mommy and daddy will come back
- More independent than my son b/c they have learned to "do their thing" in their own home
- B/c there are two of them, it's less expensive than daycare
My sister loves the flexibility of a nanny b/c if the girls are sleeping when she needs to leave, she doesn't have to wake them up to get out the door. She also loves that if she needs to run an errand after work, she can do so without worrying about whether or not she's running "over" her time.
There are a lot of factors to consider. I would strongly encourage you to go look at different day care options- look at home-based daycares and center-based b/c they are very different and people usually feel strongly in one direction or the other. You should research different nanny agencies and see what they have to offer. You'll know which option feels right for your family.