Try:
In the controller:
ViewBag.Accounts= new SelectList(db.Accounts, "AccountId", "AccountName");
In the View:
@Html.DropDownList("AccountId", (IEnumerable<SelectListItem>)ViewBag.Accounts, null, new { @class ="form-control" })
or you can replace the "null" with whatever you want display as default selector, i.e. "Select Account".