It really depends on your play style and approach. Maybe pick the three that you like the best, then test them out for a few minutes each in PvE, or with a close pre-built design in PvP (very helpful). It also depends on whether your longterm goal is to design a strong PvP build, or a more focused PvE character.
The Ranger is a very versatile and effective profession, yet not necessarily the most powerful, which puts some people off. It's probably the profession which gains the most from a player whose approach focuses on timing and patience, with Mesmer being a very close second.
Expertise lowers skill point costs over time, allowing the primary Ranger access to a plethora of skills that are very cost intensive for those who choose it as a secondary. Wilderness Survival is one of the most versatile attributes in the game, with skills that are good for the lone wolf as well as the support player. While having strong Marksmanship is always important, a bow on it's own just can't compete with the Warrior and Elementalist for damage per second - so the challenge is to design a Ranger that focuses either on skills which enhance bow damage and response time, or on skills which are complementary to a party of other damage dealers, spellcasters and healers.
In party based play, Rangers are often misunderstood and underestimated, imho. Like Mesmers, they can very easily make life hell for just about every other class when handled well. With good timing, effective weapon choice/preparation and attention to detail, a Ranger can do extremely effective damage on the battle field - notice that the keyword is effective, not powerful.
Sometimes all that a Healer or Warrior needs is an extra second to make the difference between victory or defeat, and the Ranger can give them that. Preparing an arrow with interruption or enchantment breaking skills and striking that Elementalist during mid windup can change everything - but it's not easy to do.
And that's partly why you read the "how difficult it is to be a good ranger and how easy it is to be a sucky one" comments so often. The button mashing Warrior, nuking Elementalist and spamming Healer type of player just doesn't have the patience for a Ranger... it requires subtlety and thought in both their build and ingame strategy, in varying degrees. If one approaches a Ranger as simply a long-range Warrior with a bow, then they aren't going to be very effective in either PvE or PvP.
Rangers are not designed to be tanks, spellcasters or healers - they play a unique role. They are better felt, and not seen. When a Ranger is doing their job really well, nobody really notices... on either side of the battlefield.
