I use a Ravenspring because we got a good deal on them when a bunch of us went together and bought as a group.
Kokatat makes an excellent suit but it tends to be the most expensive of the brands. It seems to be the choice of most of the kayak instructors. The expedition version is top notch with many excellent features. You will see many extreme expeditions using them - but that is in large part because Kokatat sponsors most of the expeditions with at least free suits. It does give them lots of good feedback on the requirements of a good expedition suit and they have been refining their suit for a long time. You can't really go wrong here. The gaskets are readily repairable in the field. - an important consideration for expeditions.
I have also heard good things about Palm. They are new to the scene but several people have made positive comments about them. I have not seen any of them myself.
Things to look for.
I like the idea of having a hood as part of the suit. One less thing to manage. A hood with a small visor is most useful - like Kokatats.
I prefer ankle gaskets as my feet get too hot and I don't like my feet trapped in wet sweaty neoprene all day. But the ankle gaskets on non-booty suits can be painful - cut off circulation if too tight and the suit is much harder to get into and out of.
I like having a relief zipper - although that is potentially an extra place for failure. Kokatat makes a half moon zipper for ladies......
I like suits with a zipper that closes to the down end of the zipper - not on the up side where it is dificiult to manipulate with my bad shoulders. Mine closes on the back side of my right shoulder and that is the feature I dislike the most about my suit.
Some like two piece - a dry top and a dry bottom. Allows greater flexibility like layering - where the top not the bottom or vice versa. But it restricts mobility in the torso and increases fatigue with torso rotation.
Like many tings it depends on what you want to usse it for and how much you are willing to spend to get that last nice feature.