I have only had kidney tables. I think I would like a horseshoe table better, because I sometimes feel far away from the students with my kidney table. I also feel like the horseshoe table spreads the students out a little more.
I think it depends on the grade you teach. Older children can reach you with the kidney but little children cant. I have taught upper and lower and had both-I had to trade my kidney when I moved down because my students were so far away from me.