When deciding on the best destination for a 301 redirect, there are a few factors to consider:
Relevance: Choose a destination that is closely related to the content of the old page. In this case, since the old page was optimized for garden weddings, the new destination should also be relevant to garden weddings.
Traffic and ranking potential: Choose a destination that has the potential to receive similar or more traffic and ranking potential than the old page. In this case, since the old page is not ranking well, it may be better to redirect to a page that is already ranking well for similar keywords, such as your outdoor wedding packages page.
User experience: Consider the user experience when choosing the destination page. Will users find the new page relevant and useful? Will they be able to find the information they need easily?
Business goals: Consider your business goals and which page will better serve those goals. In this case, if you have a different location with a garden setting that is available for weddings, redirecting to that page may help promote that location and increase bookings there.
Based on these factors, both options you mentioned could be viable. If the outdoor wedding packages page is already ranking well and receiving traffic, redirecting the old page to that page could be a good choice. However, if you have a different location with a garden setting that is available for weddings and you want to promote that location, redirecting to that page may be a better choice.
Ultimately, you should choose the destination that aligns best with your business goals and provides the best user experience while also being relevant and having potential for traffic and ranking.