I would go for a EW type as they are continually changing in brightness and generally have short periods. Possibly VW Cep (mag. 7.2) if you are using a camera lens, this has a period of just 6h 40m so a full orbit can be captured in one night, it is also circumpolar from the UK so can be imaged any time of the year. Or possibly NR Cam (mag 10.76) if you are using a telescope for similar reasons, circumpolar, period 6h 8m.
What camera, lens/telescope are you using?
Before you take a time series in anger you will need to determine the exposure/iso you need for different magnitude stars, making sure you allow some spare space at the top end to take account of non-linearity in the camera, different star colours and atmospheric transparency.
James