birch sap is the main one everyone knows about .
where your missing the point is the sap rises all year long because thats how it feeds the tree, what we are on about is the so called spring rush which is when the tree causes a large but slow lift of sap, the trick is to cut the hole at around 300mm or a foot off the ground level, but if you miss it just drill the hole at three foot and the same effect works there too.
i take it you already have a viable recipe, if not just say so and i will throw on out for you that does work, or we can just boil down to a thicker syrup as per our canadian colonists do, works the same with birch and the others mentioned below.
trees you can also tap are silver birch and white birch are best the other birches are less sweet.
sycamore is my favorite but its hard to do often, plane or london plane can also be tapped and the walnut tree is tapable too
and lastly our canadian colonists have had some moderate success with with a tree family called maples, a true maple for tapping is called a sugar maple you can also find these either the sugar type
standard showy maples can be tapped they work quite well depending on its size and quantity removed