Here are some of Tsundere/Kuuderes that I really like and recommend.
Tsunderes
1. Mitsuki from the fandisc, Princess Evangile W Happiness, she appeared in the original game, but it's the fandisc where she gets the her own route.
2. There is also Rin from My Fair Princess
Kuuderes
3. Rikka from Hoshi Ori Yume Mirai
4. There is also Toa from Wagamama HIgh Spec
5. Shirone from Trinoline
6. Riku from Sorcery Jokers