If you are looking for mostly makeup, go for Ipsy ($10) or Starlooks Starbox ($15). They are both almost always makeup centered and have great customer service. Both ship middle of the month
If you are looking for food, then Goodies.co ($7) is the one for you. It is inexpensive and they send a lot of stuff. Great customer service and ships at the end of the month.
If you are looking for nail goodies then go with Julep ($19.99) or SquareHue ($21). Both do polishes and/or nail related items. Good customer service and both ship near the beginning of the month.
If you are picky and want to manually choose your own, go with Beauty Army ($12). You get to choose each month. These are slow to ship but I have never had a problem with an order.
If you want a balanced mixture of stuff do Sample Society ($15). They tend to give out one scent, one makeup item, one hair item, one skin care item, etc. Amazing customer service, they ship the first week of the month.
If you want freebies that you have to work for then sign up for Influenster and BzzAgent. You have to qualify for these and they are shipped out periodically.
Others:
Birchbox ($10)has ok stuff but I have been frequently disappointed personally. They do have a points system in place that most others lack so that is nice.
PopSugar ($35) is popular but not my cup of tea. It's much more expensive and there seem to be a lot of customer service issues.
Glossybox ($21) usually has great products but their customer service is a nightmare.
Cravebox ($10-15) is subjective although most people have been disappointed lately. They have themed boxes so that has to be chosen individually.
The Look Bag ($12.95) has had a slew of problems and I can't recommend this one at all.
Little Black Bag ($49.95) is popular but you have to do online trading to get the bag you want. It is more expensive but you end up with purses, jewelry, etc.
The boxes I look forward to the most personally are Ipsy, Starbox, Goodies and Squarehue.