Hey, I'm Blame Yo Jungler (previous accounts: Chaz19 & GetRektGGEzLife) from EUW and Vi is one of my most played junglers. Vi can be played as an AD Bruiser, or an AD Offtank. Some people play Vi as full tank but it's really much better to go Offtank since Vi has strong damage with only a few items. She has the ability to do a strong level 3 gank and is decent at duelling due to her W and her passive shield. Mid game is where Vi excels when she has her ult, she can completely begin turning the game into her favour. Late game Vi is a beast since she is tanky as hell and also does a ton of damage and shreds tanks due to her W.

Pros

Strong at all stages of the game
Her ult is definitely one of the stongest and can completely take a carry out of a fight
Can be built bruiser or offtank and still be successful
Has a gap closer
Good at duelling
Has %max health damage and armour shred to deal with pesky tanks

Cons

If you don't land your Q, the gank is often unsuccessful
Invulnerability cancels your ult and cooldown isn't refunded
All AD damage = easy for enemy team to itemize against

Explanations for each rune and why I think these are the most optimal for Vi:

I used to run an Assassin page, but honestly, Vi has enough base damage, and the tank runes allow her to stay alive for longer. Staying alive longer = more DPS. The red runes barely even increase your DPS honestly. After all , you cannot deal damage if you are dead.

Tank:

Aftershock - procs after you hit a Q and R. Gives a lot of armour and MR but also damage! Probably stronger than Electrocute.

Shield Bash - Vi's passive shield procs very frequently so you will often make good use of this bonus physical damage.

Bone Plating - a bit more tankiness, especially good in early game duels and ganks for staying alive.

Revitalize - Increases your passive shield which is great since it gets procced so frequently.

Triumph - Great for every champion.

Legend: Alacrity - Gives Vi more DPS and stacks quite fast.


Assassin:

Electrocute - this keystone is perfect for burst/assassins like Vi. You always initiate with your combo which should proc it within seconds.

Sudden Impact - This is procced by Q and R therefore it is taken. Magic pen and Lethality are too good to pass up if the champion can achieve the condition for this rune.

Zombie Ward - Vision and adaptive damage. What's not to like?

Ravenous Hunter - Spellvamp gives Vi more duelling potential.

Legend: Alacrity - Attack speed is nice on Vi because of her w procs - it gets procced more often with more AS.

Coup de Grace - Good on any champion that deals damage. Could win you a 1v1.

Vi is a strong jungler at the moment as she smashes tanks to pieces whilst being tanky herelf and is also very fun! Enjoy!