I don't know about the 30% number (it started circulating yesterday with no source), but for your question:
I have United because my employer offers me United. That's it. At my pay level, and with no dependent family, I have the option of paying between 60 and 140/month for various plans offered by United (employer pays significantly more than that for me, every month). The cheapest plan (60) is absolute shit, so I pay 80. I also pay a few dollars more for access to pharma, dental and vision.
But of course, the catch is that this is just insurance, not medical payment. Seeing a specialist costs 40/visit, one month's supply of one medicine costs 30, going to the ER cost 100-150 for the visit plus whatever for the procedures, a tooth extraction at the dentist cost 200, etc.
I've been mostly fine in terms of denials, though they've got *much* stingier about medicine supplies.