I think it depends on lots of factors, such as time of day, needs of client (if you know them), etc.
For instance, I wouldn't want to use a blend that is too relaxing early on in the day. A nice blend for summer is orange, lemon and lime. If there are a lot of colds around, I may use ravensara or even some Olbas Oil with a drop of lavender to soften it.
If I'm expecting someone in the early stages of pregnancy,I may play safe and use mandarin. Often, if I have lots of clients all day, I may use something like rosewood (or ho wood), with a little grapefruit or orange during the day, adding some lavender to the blend in the evening.
A favourite Christmas blend is frankincense, clove, cinnamon and orange.
Lesley