I find that whatever age you have your kids tends to work out.
Our family is blended so that changes things up a bit - my step-twin oldest children (my son, his daugther) are 4 months apart. They are in the same grade at school and their circles of friends overlap. They are as different as night and day but at age 15, they've known each other for 12 years and have been siblings for almost 10 and still seem to like each other in a funny, antagonistic way.
Our next kids, two boys, came 6 years and 8 years after their older siblings. They are 22 months apart. Our youngest was very much a surprise but I'm glad that it worked out this way because those two are very close and I'm glad my second son has a buddy because I think that trailing 6 years behind a pair of older siblings would have left him in the dust. If it had been just my oldest son and then my second I think that would have been different but to have one trailing many years behind two the same age would have been out of balance.
I will say that the 6 year difference made me able to attend to my oldest son and my second like each was an only child. Because the older kids were in school, my 2nd son had my undivided attention when I was on maternity leave while my youngest had to share my attention. My youngest is the most well-adjusted, easygoing little guy in the bunch so maybe sharing my attention from the get go was a good thing.
I am the 2nd oldest of 5 kids born in a 6.5 year span. My older sister and I are 23 months apart and are practically strangers. My younger sister and I are 4.5 years apart and practically share a brain, proximity in age doesn't really affect how close siblings will be.