Agree that it's very much down to your baby's preferences, but we were recommended Aptamil by my SIL who works in a nursery, as that's what they use for their babies.
We found that the Aptamil poo is soft and korma-like, similar to breastmilk poo, but there is a tendency for it to get quite runny and squishy, which means it oozes out of the nappy a bit. My kids have been absolutely fine with it, so we've never needed to change.
We did try the Aptamil hungry milk once during a growth spurt and that gave my son constipation, so we quickly stopped that one!!
Another difference is the frequency of the poos.... A friend of mine uses SMA for her little girl and only gets a poo once every 3-5 days, whereas our Aptamil poos occur at least once a day.