Among the most popular maternity brands one name stands out - Isabella Oliver. Not among the most affordable, but definitely among the highest quality and style. I had the chance to review the Electric Blue Knotted Tunic. Since I am pretty petite, it even doubles as a dress for me. It perfectly shows off the bump and is both flattering and comfortable. I have received quite a few compliments on it already. The fabric is extremely soft and it doesn't have any annoying seams your belly won't like. Looks great as a dress, here is proof:
It was really hard to choose one thing at Isabella Oliver Maternity. The selection is vast and there isn't anything that doesn't look good. I particularly like their chic wrap maternity tops that are on sale at 30% off until midnight tomorrow, June 22nd!
Isabella Oliver dresses are even cuter, albeit way out of my price range. This one at $179 is great for a wedding, dinner out with husband, or any occasion really. There are a lot of other, less body hugging styles as well. 
If you are on a tight budget for pregnancy, Isabella Oliver may not be for you. With the exception of perhaps a couple of staple pieces that you would wear a lot (pants/jeans and layering tops), it may be not worth the price tag. If you have the room to splurge though, this is a great brand for you. You pretty much can't go wrong with any piece they make, it all looks like it is fresh off the runway.