Anything can pair with water forms. On avg they are kinda hit or miss but given the right forms to balance them and the right player/situation and nearly all of them can be quite powerful. They certainly aren't as powerful on avg as they should be since they're water locked, ie, most can't go on land but each can be nice.

If you're interested in exploring I'd suggest Water Major and Defense minor or simply hope for something like Sea Snake in second from top tier. Shark, Eel, Manta, Walrus, Lobster, Orca, Dolphin, Squid and any of the top tier defense forms can handle a lot of situations using gills and flee/heal tactics. Not to mention, you can track a ton of tough mobs to water or swamp rooms.

The above order is also my order of favorites. I can tell you that Orca, Dolphin, and Squid are meat to dex or STSF builds on avg. Lobster and Walrus have pretty fair damage redux and are amphib, so they're more versatile. Manta and Eel both dodge like mad, superior to Dolphin and land more hits and more painful hits. Shark, imo, is the king of water forms with one big exception being that it has lag on the swimto that the other forms don't have but it by far out damages any other forms out there and can eat dex and STSF builds with only moderate prep. There was a Nexun some time ago, Guargoux, that posted some fights he had with it.

Last bit I'd like to offer is that if you don't get forms you're happy with at first, give it time, get the feel for them. This may mean several hours of time to fully understand what you can do with it. I know from experience, different forms grow on you.