I still think slaughterfish can destroy everything. If they need to get to land, i'll go into Spore's creature creator and stick some legs on there!
Don't know if you need to do that. I've seen slaughterfish flopping around on land before in Oblivion. Seemed like the critter was heading in my direction too, tenacious buggers.
I'd choose Cliff Racers, because they sing so beautifully.
Also, choose wisely: Remember you will be FRIENDS with the one you support. They will follow you to the highest summit and deepest, err, depths of hell, They will be your buddies
. Throughout the whole story.
Originally I was gonna pick mudcrabs, but if they're going to be a tag along, I'd want a cliffracer 'cause I wouldn't want to have to wait all day for the mudcrab to catch up.
Cliffracers could probably provide good aerial support too.
I'd pick the mudcrabs, but only if I can have http://images.uesp.net//1/19/Giant_Mudcrab_Size_Compare.jpg mudcrab from greenmead cave.
Maybe I'm mixed up in my lore somewhere, but didn't the Oblivion crises resurrect the Mud Crab King when the dremora sacked Ald'ruhn? The giant mudcrab shell that the Redorans made their HQ out of? If so, I'd sooner want that mudcrab on my side.