Mieluummin means rather — and it goes with a verb, so you say what you'd rather do. Than is kuin, as in unit 10:

• Juon mieluummin teetä kuin kahvia. — I'd rather drink tea than coffee.
• Menen mieluummin mökille. — I'd rather go to the cottage.

The top of the scale is mieluiten — most of all, best: Juon mieluiten vettä. — Best of all, I like to drink water.

English uses would here; Finnish needs nothing extra — the plain present does the job.