I'd try the main story, for free, as single player. Do keep in mind the expansions are really different from central Tyria in multiple not-so-fun ways. Then, I'd try PoF single, and then I'd skip HoT altogether, since it's an insufferable map with insufferable mobs, few people to help for the story mission and overall tedious difficulty for someone who's just now starting the game. The game does get incredibly grindy as it progresses, and it also doesn't teach you much, so be prepared for spending dozens upon dozens of hours grinding for not a lot of progress if you're playing solo on the expansion maps (unless you've been playing for a long time and are one of those who "can go through the tangled depths with a low -level character, because it's not so hard really, all you need is 2-5 years of practice and meticulosly stidying every mob you're facing in this map, you noob").
Long story short, you have to be prepared for:
- Watching hours and hours of youtube and reading a whole bunch of tutorials, because the game won't teach you what you need to know to progress. This is an undeniable fact, not even an exaggeration.
- Getting used to needing to be helped by older players and having them teach you what the game doesn't bother to, which is nice of them, but you do get tired of _constantly _needing to find someone who's played the game for years in order to do things you could easily figure out in central Tyria. It should not be that way, it ain't fun for anyone. I've seen a big percentage of these long time players being annoyed by noobs, and I don't blame them, but hell, I could never blame the noob: the game isn't helpful for a new player.
You'll find most of the people who defend the grindy maps are the people who have been used to it for years, so, I'd make sure I would enjoy this level of grind beforehand. And, if you already bought the expansions, best of luck in the jungle maps and stories.