I must say Geldeston Locks is one of my favourites and one of the best pubs on the Broads IMHO. However its maybe not quite so good for boats passing by as its at the end of the navigation and fewer boats can get under Beccles Bridge. Going North from Oulton Broad by road I guess you would have to go through Yarmouth. Horning is probably the best place on the Broads for sheer volume and variety of boats, yachts and everything else in between passing by. The Swan and New Inn have riverside terraces (rather than gardens) but riverside activity a plenty. Likewise the terrace outside the Hotel Wroxham is a real grandstand for boating activity.
I would heartily endorse the Surlingham Ferry as has been mentioned. Excellent pub and a fair bit of traffic on the main river.
The Bridge at Acle is excellent but the garden is partially screened by the flood bank so you don't get such a good view from your table. I love the Ship at Reedham although since the fence was erected by the river the view is a bit restricted particularly if those large boats are still there. You do get the trains as well. Rushcutters is good too but river traffic limited by the low bridges.
It maybe depends what the OP is looking for, for example is distance an issue, are children involved etc etc. Which is more important, the food, the garden or boating activity. Plenty to think about!