Augustus (reigned 27 B.C. to 14 A.D.)
Claudius (r. 41 - 54 A.D.)
Vespasian (r. 69 - 79 A.D.)
Trajan (r. 98 - 117 A.D.)
Hadrian (r. 117 - 138 A.D.)
Antoninus Pius (r. 138 - 161 A.D.)
Marcus Aurelius (r. 161 - 180 A.D.)
Diocletian (r. 284 - 305 A.D.)
Constantine I (sole Emperor 324 - 337 A.D.)
Theodosius I (r. 379 - 395 A.D.)
Justinian I (r. 527 - 565 A.D.)
Heraclius (r. 610 - 641 A.D.)
Leo III (r. 717 - 741 A.D.)
Basil II (r. 976 - 1025 A.D.)
Augusto was not an Emperor, he hold the title of Prince
The first Emperor was his sucessor Tiberius ,In my point of view, the best pagan Roman Emperor was Claudius, his realm was thoughtful .
The best Christian Emperor, Constantine,