Manuka oil may be a good alternative to Tea tree oil as it is anti-viral, anti-fungal and highly bactericidal across a wide spectrum. It's scent is very sweet and 'gentle'. It can be used in situations where the stronger and more medicinal smelling oils might not be welcome.
Manuka essential oil has a woodsy, cedar like smell that is much warmer than Tea tree oil. There is evidence indicating that it is up to 20 times more potent than Australian tea tree oil