Electrocute is the safest choice. I would recommend it instead of Dark Harvest or Aftershock. You don't want to pick Dark Harvest due to its rework, DH is better for laners and its still viable for junglers like Kha'Zix but useless on Vi if you aren't smurfing and you are 100% sure that you can stack it early. Aftershock is good if you want to go full tank but you lose a lot of 1v1 potential and kill possibility.
Sudden Impact is very good with your Q and because you are building ghostblade or duskblade it gives you bonus lethality.
Ghost poro is the best early game rune. You can place the poro in the pixel bush (pixel bush is the small bush in the river) that is on the Blue Buff side of your jungle and if the enemy jungler goes for the scuttle you can spot him. This also allows your laner not to ward the bush at 1:20 and safe his ward for his lane.
Relentless Hunter helps you go around the map quicker, finish your camps quicker wich means you can gank or go for objectives way faster. This rune saves a lot of time and time is the most important thing in the game.
Triumph can help you dive safer and safe you from dying to the enemy laner if you are low and he ignites you.
Alacrity gives you bonus attack speed when you kill jungle camps, champions, minions, and objectives (without towers). This rune helps you hit your combo (Q+AA+E) easier and clear your jungle easier.