I am pre-op, but I am drinking the unjury chocolate Splendor Protein shakes in the morning. I wanted to try to find something I liked before surgery. I tried the chocolate Amplified from GNC, but thought it was terrible. I also tried the Body Fortress Super whey Shots (from Wal-mart). These were also terrible. I seem to be on the picky side when it comes to these drinks.
One nice thing about Unjury is that you can order a starter kit which comes with packets of their flavors, a shaker bottle and a thermometer. They have a chicken Soup one that can be heated, but only to 130 degrees. I didn't care for it too much, but online it gets good reviews. As far as I know, you can only purchase Unjury online - www.unjury.com. My dietician recommended this brand as it is high quality. She recommended mixing the strawberry flavor with diet lemonade. I haven't tried that yet. You can mix the unflavored or fruit flavors with drinks like Crystal Light, so that gives you a few more options.
I haven't tried Isopure yet, but that is one that I would like to try next.
My surgery will hopefully be in October, but like you, I'm nervous about the liquid diet. Also nervous about getting insurance approval. I have done everything I'm supposed to do, but they can always find a reason to say no. I will have to do liquids two weeks before surgery, then a few weeks after, as well. That alone should induce some rapid weight loss.
Congratulations on your surgery date and best of luck to you.