I was going to say birch for all the reasons that everyone else has already said, but I think instead I'll say Elder.
I just went through the list of uses to which I've put this tree, and its huge! Its wood is very light - and the stems are straight and hollow, and filled with pith. This pith makes great tinder, the stems can make good bow drill spindles, and when hollowed out, the stems can be used for making pipes, blowpipes, straws etc. The pith can also sometimes be extratced as a solid piece, which makes a very good natural fishing float.
The leaves contain a strong-smelling chemical that repels most insects when rubbed onto skin. They are also good (in small doses) as they act as a diuretic and help relieve constipation. They also make a very nice green-brown dye.
The bark is a strong purgative - so this might be of use, although I've never tried it!
It does however also make a good brown dye, and a decoction of the bark and leaves is very very astringent, and closes up cuts and wounds quickly.
The flowers are very tasty! They can be used in drinks, desserts etc, as well as in perfumes and scents, but they also have an anti-inflammatory effect and are good for sore eyes, rashes, blisters and burns/scalds when used as an infusion/ointment.
The berries (when cooked) are also very tasty - very good in jams, pies etc, but also when boiled up with cloves they make one of the best cough syrups I know. they are also very rich in vitamin C - second only to rosehips in wild plants.
No wonder elder was often referred to in ancient herbal texts s the mother-tree, or 'nature's pharmacy'!
(A small bit of advice/superstition though - never take living wood from the elder tree without asking its permission - preferably never at all - only take fallen dead branches/winter prunings etc. there are many superstitions in Northern Europe that because of the tree's 'magical' properties, it is host to the fairy people/dead souls/evil spirits, and cutting the wood will release these and bring misfortune upon the cutter. Just a note of warning :shock: :rolmao: )