My old consulting co: Tucows, through a friend's reseller site, then DNSMadeEasy; self-hosting (low volume, little content); Google Apps for email. Current co:

My old consulting co: Tucows, through a friend's reseller site, then DNSMadeEasy; self-hosting (low volume, little content); Google Apps for email. Current co: GoDaddy. Partners chose based on cost, stayed based on service. Slowly moving away to benefit from better app integration on other sites.