Best model to purchase for Bay Area?

Hello. Looking to purchase a Brompton for commuting purposes in the SF Bay Area. Some riding will be in SF and some in the East Bay. I'm new to this sub and new to Bromptons, so I'm also wondering if the components are different on a 6spd vs a 3spd or 2spd.

I commute on a Surly LHT now but will soon need to take public transit sometimes and also bring the bike indoors to an office, hence the search for a folding bike.

Thanks.