In my opinion the longer you wait to space out your first from your second the more your first child gets used to being an only child and a lot harder the transition when it comes time to sharing toys/attention and so on.
My siblings and I are all 2 years apart and I always liked that. Of course I am the youngest and 4 years different younger than my sister. We have a brother in the middle. Growing up I was much closer to my brother. My sister always made me feel like I was a nuisance to her and she had much better things to do with her time. However now as adults we are very close and mostly because we both have children around the same ages.
But back to my girls they are 2 years and 2 days apart. During pregnancy it didn't really effect my relationship with my oldest. However, there were nights where I was just extremely exhausted and my husband was very good at helping me out. After birth, my daughter didn't really have anything to do with my daughter. It didn't really change her lifestyle however I don't know if it was the age or what but she seemed to get more adventurous, I thought because she knew I was busy with the baby. All this being said, she was never mean to her sister. And, yes that first year it was pretty tough balancing things out, but then I couldn't wait to get out of that baby stage with my oldest too. After my youngest turned a year is when I really saw the bond grow between my daughters. And now that they are 5 and 3 I am so happy I had them when I did. They have more common interests and are able to play good with each other.
But regardless of what you choose, in the end it will work itself out and you will love each and every one of your children just the same.