if get it to 100 ?

and say i complete thieves guidl quest line or 100% fortify illusin and get invisibility woudl even be worth perking sneak ?

My Khajiit combined Sneak and Illusion (with a little One-Hand for epic backstabbing), and he's a nearly unstoppable force. But if your character has other abilities, what works for him may not be something you'd want.

well the righthand tree that gives damage bonuses is really powerful.
so powerful most people consider it OP

with illusion you dont need the lefthand side at all because of invisibility.
but the roll is nice for moving faster.
shadow warrior forces enemies to lose sight of you, if you ever get caught or whatever.
But nothing I consider essential.

Sneak is most certainly worth perking.

I take every perk in Sneaking except the last one and the 4 non mandatory stealth augments in nearly every character I play because I figure they all would likely want to remain unseen from time to time.

Yeah, I even had a few barbarian warriors max sneak, because I like to switch things up from time to time.

but if use muffle and invisibility spells

and say i dont want kill any one

Sneak perks will make not killing a whole lot easier.

With muffle, invisibility and sneak perks, you can just creep through a city in broad daylight undetected.

if you intend to use invisibility spells and muffle spells and to be at lvl 100 sneak, most perk will be overkill.

only the ones that dont affect how easy it is for enemies to catch you will really be of any use.
IEsilent roll and all the sneak damage buffs.

but with invisibility level 100 sneak and muffel enchant on shoes ?

I'm going to assume your using Vanilla as Skyre is an obvious "yes" to perking it.

Vanilla, no. Useless skill tree.