Based on my observation, I would nominate the best designed stations to PWTC and Bukit Jalil stations of the STAR line. Both of them are elevated stations, and come with aesthetic design yet functional elements.
1) PWTC Station
PWTC station is the only station that was built over a river, which is Sungai Gombak. It is an important station, more so when the UMNO delegates converged to the PWTC for their annual Perhimpunan Agung (General Assembly).
2) Bukit Jalil Station
Bukit Jalil station plays a very important role in ferrying sports enthusiasts and fanatics to the different sports venue, namely the National Stadium, Hockey Stadium, and Stadium Juara. Besides, the venues were also often used to hold concerts of international pop stars. Its location is so strategic that I thought it was very well planned and built.
Bukit Jalil station has the reputation of making an appearance in the Hollywood movie, Entrapment that was starred by Sean Connery and Catherine Zeta Jones. However, fame had to come with sacrifice as it had to take up a "stage" name by the name of Pudu.
Note: STAR line has been renamed as Ampang Line, and PUTRA line as Kelana Jaya line ever since it was managed by RapidKL in 2004.