Fisrt, what isn't on the web (birth dtes, marriage dates, maiden names) can't be hacked. So, I keep all of my data on my PC and just use Ancestry for records. Every year or two I build a GEDCOM, privatize it and upload it to Roots Web World Connect.
Second, if Ancestry.com triples their rates some year, I can tell them to go whistle and still have my data.
Third, Roots Magic, which is my favorite (I tried FTM and PAF) has custom reports, ease of entry tricks and problem reporting capabilities Ancestry doesn't have. The others probably do too.