Definetly CCS, I feel way to confused sometimes when it comes to TRC, I usually like knowing some info on the characters, but I hardly know some. Also, I have a cute fetish, and CCS was too cute ^^;. I doubt I'd even read TRC if Sakura and Syaoran were not in it.
I also think the plot is quite unstable, and too Pokemon esque for my liking, I'd rather see some real angst or some character development, rather than the whole '1 villian=1 feather' formula. Sue me, I'm a sucker for more deep plots.
However, TRC is really good as well, but you have to have real patience, and have to like teh whole travelling scenario.
Also....Syaoran and Sakura seemed more lively in CCS *dashes off from the TRC fans*