I think VGC is definitely going to be my vote as well, especially since I feel that an entire community doesn't get enough love from smogon despite being THE competitive format. Many people who are passionate about VGC may not have the means to play it, either due to not having a switch or being able to travel easily for IRL tournaments. This leaves them with one sustainable choice if they want to still play: tours on smogon. The unfortunate thing though is that there is very little doubles representation in smogon overall (the singular doubles format here comparing to the nine singles formats supporting that point) even though it has shaped entire communities in the past. While I don't have an issue with smogon being singles oriented, I do feel that it shouldn't come at the cost of a whole community and that adding even one more doubles format opens up a whole new community of people.
Another key point I want to bring up is that singles skill does not necessarily translate to doubles skill. If someone is a very good player at OU and spend the majority of their time training there, they will also be relatively good at other formats. This lets them easily have a backup plan if they don't get drafted for their main tier. If they aren't picked for OU, then they can still try UU, RU, NU, etc. for spots because they still have likely honed the right skills to compete at a strong level in those tiers. For doubles players, it is all or nothing. In the current state of BLT, if you are a doubles main and aren't picked for DOU, chances are you probably won't have a chance to play in the tour at all. The skills you hone for doubles will likely become completely irrelevant in any other format in BLT, except if we added VGC. Then, doubles players don't just have a fallback option but an alternative that actually addresses the powers of many prominent players on the site.
Thirdly, I feel that VGC is inherently going to be an extremely competitive and lead to a very interesting draft section. Not only will experienced doubles players try to take the slots but a lot of newer rising stars will be attracted by the idea of VGC, and because this is a very unexplored area in big smogon tournaments right now there will likely be a lot more sneaker picks in VGC than if most other singles formats were chosen. This poses the managers with far more options to take either safe picks or newer picks with the newer picks having a higher chance to shine during the tour, which is something any tournament tries to aim for. This will also bring far more versatility into BLT, creating a tournament that appeals to a larger audience for the future as well.
While it might not necessarily be the format many of the players here main, adding VGC has a lot of potential upsides both for the doubles community now and the overall size/diversity of BLT going forward. VOTE VGC!!!!