The most excellent prayer is that in which the duration of standing is longer.  

قَالَ رَسُولُ اللَّهِ ﷺ أَفْضَلُ الصَّلاَةِ طُولُ الْقُنُوتِ  

The Messenger of Allah ﷺ was asked about the prayer which was most excellent. He said: That in which the standing is longer. (This hadith is narrated by another chain of transmitters too.)  

سُئِلَ رَسُولُ اللَّهِ ﷺ أَىُّ الصَّلاَةِ أَفْضَلُ قَالَ طُولُ الْقُنُوتِ قَالَ أَبُو بَكْرٍ حَدَّثَنَا أَبُو مُعَاوِيَةَ عَنِ الأَعْمَشِ