Is there a reason you haven't knit with wool? Are you allergic?
Personally, I love Manos del Uruguay for several reasons, the colourways are beautiful, it is made by a co-op in Uruguay that supports the local women there, it's merino wool and quite soft and warm. Drawbacks: It's expensive, I made an afghan out of it and it has pilled like mad and it's not easy to wash.
I also like Paton's Shetland Chunky for a less espensive yarn that comes in a million colours, is good for larger projects like throws and it is easier to wash.
Malabrigo is a favourite of many people on KH. It is similar to Manos, but a lot softer. I bought some of the lace weight as a gift for my aunt (i should have bought some for me too!) and she loves it.
Personally, I like my yarn to have some wool in it. It depends on the project of course and if you are allergic then it's not really an option, but I really like the durability of wool and it's many other great qualities as well, such as warmth.