I was shopping for the C-shaped vibes a while ago and decided to go with the We-Vibe 3 instead of the Tiani. Granted that when I was shopping, the Tiani 2 wasn't released yet. With a bit of googling I found a few comparisons. Here's one which looks informative: Offsite Review Link.
Unfortunately though it only compares the We-Vibe 3 and the original Tiani.
If you actually read the reviews you will find that some do mention some comparisons and suggestions as to which one is better. I would suggest if you're really interested in them to read all the reviews and decide based on them. I know there's many reviews but it's really the best way to remain informed. Plus if you're collecting Eden Fantasys points you can rate reviews and write comments and get more points