It really depend what you want. Because you are staying at fengjia, do u want to also shop at fengjia night market? Yizhongjie also like a night market which I can't finish in 2hrs.
Day 2: do u want to focus on Puli area? Then stay at cingjing or puli? Example places to go is like sun moon lake, 九族文化村(theme park), paragliding, and somemore.
Day 3: you can focus on sunrise at cingjing if u stay at cingjing coz it will b abt 3 or 4am. Then cingjing farm, carton king, little swiss garden at cingjing.
All these is only possible if u book transport. Above is just my personal opinion as I been to taiwan 4 times in the past 2 yrs. Apr i am going again.