I originally wanted a 2-2.5 year ago gap between my bubs but life doesn't always co-operate! Two miscarriages later and my son is getting a baby brother soon, he'll be right on 3 years old.
Although this isn't what we planned, in retrospect I think it's perfect for us. When I was preggy with the miscarriages I remember being quite worried how I'd cope because DS was still going to be quite young (21 months and then 25 months). But this time around I feel he'll be the perfect age. He seems to truly understand what's going on. He's far enough from being the "baby" to hopefully not feel any ownership of his old cots/toys etc, and he is sooo keen to help and so interested in babies etc. Much more independent, sleeping well generally, toilet trained etc. He will understand if I can't attend to him immediately (I hope!).
Also, apart from those practicalities, I'm also happy I got to spend 3 years just being HIS Mummy, and I feel it'll also be easier to give the baby more one-on-one time considering DS is a bit older and able to look after himself/goes to daycare etc.
Also, I HOPE 3 years won't be too big of a gap for them to play together... that's probably my only real concern about this gap. Time will tell...
But, as I said, life doesn't usually co-operate so try not to get too fixed on any particular age gaps.