So you're basically looking for visits that did not interact with evar30.
If you do option 1, in the visit it's going to look for a hit where evar30 doesn't exist. Once it finds it, it will include that visit. This means that if the visit has more than one hit, one with evar30 and one without evar30, because there is at least one hit where evar30 doesn't exist, it will include it. Meaning this isn't going to give you the result that you want.
If you do option 2, this is getting you in the right direction. You don't need to include the visit metric though. If you want visits that have no evar30, you would do this.
EXCLUDE
VISIT
evar30 exists
That would get rid of any visit that has any evar30, whether it fired or persisted. If you don't care about persisted values and just want to exclude visits where evar30 actually fired, instead of "evar30 exists" you would use the metric "evar30 instances exists".
This article by Jen Dungan has a great overview of the difference between "does not exist" and "exclude".
https://experienceleague.adobe.com/en/perspectives/the-magic-behind-the-curtain-complex-segments