I am making a new character and I am stuck. ARgonians seem really badass because they have regen health, like the Altmer and Redguard for magicka and stamina respectively. But is the DUnmer any good?

Of course they're good. You choose, doesn't really matter.
Make your own simple decisions.

Go with Argonian. They have probably the coolest options for customizing the faces out of any race.

Yes, if we're talking in terms of racials. They are perfect for thief/mage hybrids and Ancestor's Wrath has saved my ass countless times.

Khajiit!

Argonians rule...we can breath water. The most significant of all racial bonuses.

sour, I made a Khajiit and it worked out pretty well. I'm tired of the overabundance of humans.(Nords nords nords and imperials everywhere!) The khajiit made me want to play as another non-human. I'm just unsure as to which racial abilities would be better. Histskins ounds really cool,but I'm not sure as tol the effectiveness of the Ancestor

Is this serious? In my 100+ hours there has not been a single time where I would have benefited from breathing underwater.

Go with orc...and make him an assassin

Each game is different. There are times I could have drowned from some traps, plus being able to flee from enemies and them being able to follow you is nice.

Yeah, beast races and elves (mainly beast races) are rare in Skyrim. I like it though, feels special to see one crossing the road.