If you can, go for 8 speed rather than 7 and the 8 speed can be upgraded to 9 or 10 speeds. 7 is basically what it is and it does not leave much room for customization to your needs.
8-9-10 will allows you to swap cassettes easily. Closer ratio cassettes offer smooth transmission shift somthing the 7 cassettes don't do as the gap between gear teeth is greater.

Then I would always advise a Dahon as they are pretty compact, robust and use generic transmission and brake components you can get everywhere and are easy to maintain/service whereas thing like brompton (which I really like) are using specific component that you will find at brompton specialists/retailer shops.


here is my old commuter... used to do 5 to 17 miles commutes (each way).