Canon Pairing: Johnny x Rachel
In the series, the pairing seems to make sense to people that actually follow the logic of the episodes, since Johnny and Rach met first, and Johnny was the most depressed after she died, and after he met the same fate after finally getting rid of Zero, him and Rachel are reunited to be together forever.
Yaoi Pairing: Johnny x Cap
To people who are in love with shonen-ai and boy love, Johnny/Cap is the way to go X3 The two are opposites, Johnny is the hero who jumps into dangerous situations without thinking much, but has a good heart, while Cap is a smart guy who is always cautious about each step he takes, and nervous about fighting, but when going against Johnny, the other's bravery rubs off on him. Those two should be together forever, yeah, so Johnny shall not die! X3