While a lot of the differences could be due to my boys' divergent personalities, I enjoyed having a 2 yr old and a baby better.
My first was just over 2 when #2 came along. He was so sweet and helpful! He'd run to get me diapers and burp cloths and pacifiers. At first we had problems because he really thought that baby brother was going to play with him, and he loved him so much that he'd lay on him.
Now that they're older, my 3 1/2 yr old is so so sad that his big brother gets to go to school and friends' birthday parties and he doesn't. I'm really glad that this stage will be short.
We have a 2 month old now, so I am experiencing the 3 year age gap, too. My 3 yr old is still helpful. He's better at putting a pacifier in the baby's mouth, but less eager to help me get diapers and things. And he still lays on the baby sometimes because he loves him so much.
As for ME, it was harder to get back into the baby mode of waking up in the middle of the night, nursing, etc. after 3 years off. At 2 years, youi're still getting up sometimes at night, you're still in diaper mode, etc. I was really enjoying the freedom of potty trained kids who sleep through the night, and resented having to go back! Of course, I got over that.
It also depends on how many kids you want, I suppose. If you only want 2, then it probably doesn't matter much. I want to have only 2 home all day at a time, but I also don't want to be having babies past about 35. My inlaws have surprise caboose who's still in high school. He was born when MIL was 42. FIL is still working, even though he could be retired by now, because you just can't be retired with a teenager in the house!
I really don't think it's going to make a huge difference either way. But I love how my 2 yrs apart boys play together now, and that little brother who idolizes big brother will be able to do the same things soon.