For me, my easiest to read deck, that I just seem to click with is the Robin Wood deck. A customer of mine, and neighbor saw it in a 2nd hand shop for a dollar and she purchased it and gave it to me.
Perhaps it is so readable because of the good intentions by this customer? It must have belonged to someone who used it a lot too, as it was somewhat worn, but apparently very lovingly so! It came with two extra cards, a blank white card (which is common in a lot of decks, I know) and an extra wheel of fortune card. I use this deck the most, and that customer now gets free readings for life! win/win.
I know you didn't ask about oracles, but I feel inclined to include the oracle that I click with too. That is the Tea Leaf oracle by Rae Hepburn. I don't use it as often and rarely for a reading one on one--as it takes awhile to get through it. But, that said, it is an oracle that fascinates me and seems to really stir up the intuition juices in me. I use to do a reading for my most returned customers each year for Christmas--and do a 'new year' reading that would be for the next 12 mos. It always proved to be very accurate, and my customers who received it as a gift were always so thrilled that it kept them coming back. another win/win.
But, I haven't done that now for a few years.