I had a pair of CIC's, but I find that people will ultimately notice them anyway, thus they get more attention because people are curious to know what they are. The CICs functioned well, but having a smaller battery means battery life is too short. The CICs also tend to become blocked more frequently, so eventually you may have to send your CICs for servicing if there is too much blockage, thus spend more $$$.
I now have a pair of "ITC's", but they do not completely cover my ears, though they do sit on the base of the inside part of the ear. From what my audiologist told me, my current HAs are one step up in size from the CICs. Anyway, I find these HAs very comfortable to wear (sometimes I forget I am wearing them), and they have a longer battery life than CICs, and less prone to blockage.
The only downside with my model (its from ~2004), is that I have to manually select telecoil function when I need to use the phone. But, overall, I find that they work ok.
I think my next pair of HA, will be the super thin BTA - providing they are capable of functioning with my level of hearing loss. The main reason for my change, is because these "new" BTA's look modern, and may work better when using the phone.