The best way to level in Star Trek Online
The ultimate question between PvP and PvE which is the best way depends on how long it takes to complete each respectively in Star Trek Online. Pvp works nice cause there is always extra missions you can work to accomplish always a mission that rewards a few 100 skill points, for completing x amount of games, in addition to kill missions, and its relatively fast. You would avoid capture and hold while leveling map is fun but playing a single battle for 30 minutes plus for 150 skill points gets annoying, as well as ground pvp again takes a long time. If you want to level up your character you can visit here and find the most secure star trek credits.
Outside of which ones going to level you the fastest, you should also consider that you will make grips of money pvping conservatively estimate that you made at least 4-5 mill over the course of leveling, pve missions will be the same variation of kill space/ground, scan ground, and pvp while the same maps is you playing against characters star trek online credits which can be more exciting.
The best way is which ever way appeals to you. Many players do exploration missions when they first crack rank; they prefer to go into PvP with the best equipment on their ship or person as possible. They find doing exploration missions takes very little time. If you have nothing to do for a week there is no reason you can not whip to BG in a week time. Just go with your instincts. Usually 3 triplet explorations per level. 30 missions later you've bumped to the next rank. Takes a few more as you go up in level, but still pretty fast.