Keri'as ha'Torah needs 3 people to read all together 10 Pesukim. So 2 people read 3 Pesukim and another reads 4. The one who reads 4 is considered "Meshubach" -- more praiseworthy. Any of the 3 Aliyos can be given the merit of reading 4 Pesukim.

Rashi explains: The first of the 3 who reads 4 Pesukim is Meshubach, and so for the second and so for the third. "Im Lo" -- if the first does not read 4 Pesukim and the second does, or if the first and second do not read 4 and the third does, the one who does 4 is Meshubach; and if there is Revach -- more space, meaning more Pesukim and thus they all read 4 -- then they are all Meshubach.

All the best,

Reuven Weiner