Over the course of the 2 week rental, I used both baby carriers a decent amount, but around the middle of week two I had given up on one...we had found our winner! After a lot of use, I decided to go with the Beco Gemini.
I really wanted to like the Beco Butterfly ll. I wanted to fall in love with it and wear it everyday because it simplifies the back carry. There's a "pocket" that baby goes in, and for a babywearing newbie, it seemed like a dream! Now, I'm sure that the Butterfly ll works for a lot of babies, but Micah just didn't like it. He squirmed and fussed every single time we tried it. One of the times, he did fall asleep, but every other time he just didn't seem comfortable. It also hurt my back, but I can't be 100% sure that it wasn't just the way I'm built.
On the flip side, Micah loves his Gemini. Every single time I wore it he was content if not happy (these days all he seems to want is to roll around on the floor). I like the padding and the crossing straps. I love that I can do 4 carries :: front carry facing out, back carry, front carry facing in, and a hip carry. I haven't tried to put him in the way the directions say, but I can get him in from a sitting position which is working well for us.
At the end of my rental period, I went in to Granola Babies and bought the Beco Gemini in Metro Black. There are a few really cute patterns, but Alex wouldn't go for a pattern :) I am extremely happy with my carrier, and we take it everywhere! I hope you'll check out Granola Babies and maybe recommend the rental feature to a friend!