Let’s consider both options:
OPTION #1: The rider is Christ.
Advocates of this view point out that the Lamb (Jesus) was mentioned closely in context (v.1). This figure rides a white horse, which also fits with Christ’s second coming when he comes in judgment. In Revelation 19:11, we read that Christ returns on “a white horse, and He who sat on it is called Faithful and True, and in righteousness He judges and wages war.” The “conquering” of this rider is, under this view, the spread of the gospel upon the Earth (Mt. 24:14). The Greek term nikao is used of believers “overcoming” the world.
OPTION #2: The rider is symbolic for all Christians spreading the gospel.
Advocates of this view make a number of observations. First, the term nikao (“conquering and to conquer”) is positive 13 of 15 times in its usage in the book of Revelation. Up until this point in Revelation, it has been consistently positive. Second, the victor’s crown (Greek stephanos) was promised to believers earlier in the book (Rev. 2:10; 4:4, 10). Third, this view correlates with the gospel reaching all nations, which was also predicted as a precursor by Jesus (Mt. 24:14). While this isn’t the view of this author, it is plausible. This author holds to the third view.
OPTION #3: The rider is the Antichrist.
First, the archangel commands this figure to “Come” (v.1). This hardly fits with the notion that the figure is Christ, who is greater than angels (Heb. 1:4ff). Angels wouldn’t boss Christ around.
Second, John says that “a crown was given to him” (v.2). This implies that he doesn’t have the authority in and of himself. Instead, God gave him this authority. This conception of delegated authority fits with the second angel in verse 4 (“it was granted to take peace from the earth… and a great sword was given to him…”), and the fourth angel of verse 8 (“Authority was given to them…”). This also fits with chapter 13, where God allows the beast to make war with the saints and “overcome” (Greek nikao) them (Rev. 13:7). This is the same Greek word used in verse 2 to refer to the rider “conquering” (Greek nikao).
Third, this rider carries a bow (v.2), while Christ carries a sword (Rev. 19:15).
Fourth, the context of the passage deals with other riders, who are clearly not Christ or even godly angels.
Moreover, we do not see the symbolism of the white horse to be significant in referring to Christ. In ancient times, a conquering king would ride on a white horse. Walvoord writes, “In biblical times it was customary for a conqueror to ride in triumph on a white horse.” Thus for these reasons, this author holds to the third option. The rider of the second horse is the Antichrist, or some other evil ruler.
 Walvoord, John. The Revelation of Jesus Christ. JFW Publishing Trust. Chicago, IL. 1966. 126.