I've had Feel Unique for the past 3 months and they have all been great. A good mix of full size and deluxe sample size products. I also like that they are the cheapest as they don't charge for postage, and everyone gets the same thing. I think it's fair to say that the value of the products each month is about £30-40.
I've also had Glossybox for the last 3 months too, and it has been hit and miss. People get different things, so you could end up with a box that's not as good as others that month. That's happened to me twice. The December box though was good across the board I believe. I was chuffed with it anyway. Again it's a mixture of full size and deluxe sample size products.
I got the JolieBox (Boudoir Prive) for the first time last month (yes, this has to stop), and I was impressed. I think they are more likely to do brands I haven't heard of, so more luxurious than Feel Unique. Am interested to see how things go as they've been taken over by JolieBox now.
There's also another one besides Carmine - it's called Amarya. It's an organic beauty box - I got one - their 2nd. Was really disappointed - there was a full sized eyeshadow, a little travel set of skincare stuff, and some body lotion, but then the other 2 items were the little free sachets of cream you'd get in a magazine, so in effect 40% of the box was made up of stuff you'd expect to get for free.
God what an essay.
I reckon for consistently high quality and good value boxes, you should go for Feel Unique. I think their buying power probably has a lot to do with the quality of the stuff you get. If you want more luxury, go for JolieBox.
So at the moment I stupidly subscribe to 3, justifying as things that I don't fancy I save and put in stockings /presents etc. But it's ridiculous. Don't do what I do!