Not sure what skin you're referring to as void nocturne, but I'm assuming its eternum. Both it and firefighter trist are legendary, which makes them kinda cool. Firefighter trist is also a retired skin, so you can't buy it. Sadly, it's a bit old and doesn't have the same level of work that newer legendary skins have, but it does have a cool water effect on the autos and abilities.
Dark star varus is kinda cool. Really depends on how much you like that skin and champ.
Galatic Renekton is also retired, so that makes it a bit more rare. It's an ok skin, but it's pretty much just a recolor and slight texture changes. It was one of his launch skins.
Lep Veigar is cool, again if you like that champ. His W turns into a rainbow.
If you already own warden naut, you can go ahead and disenchant to get essence for the other skins. Rolling skins is great when you don't have anything you want and tons of essence, neither of which seems to be the case here.
SSW talon is meh. I'm personally not that big of a fan of the team skins, but some people really like them.
SKT Zed looks better than talon's skin, but I don't like it much either.
Sailor GP is also retired and gives him an interesting look. He has other, better skins, but it's pretty good for what it is.
Steel Legion Garen looks really silly to me. He's already bulky, that skin makes him look doubly so. It is, however, rather cool and the effects on it are good. It's not my personal favorite Garen skin, but it's not a bad one.
I would suggest determining which skins you like best and seeing what you can afford to get. It's OK to hang onto skins until you get enough essence.
