When I'm using a profile that my users might be filling out for the first time (membership form for example), I generally ask for both a work and a home address, email address, etc. How can I let them choose which one to use as their primary contact information (mail and email as well as phone)?
What's more important for your organisation? Know that an address is primary? or that it is an home/work address?
If primary/secondary is more important then I would use the "Main" location type in the profile and set it to Primary in the settings. And then make sure a "secondary" Location type exists and add that one to the profile as well.