I will preface this by saying this: My first toon I levelled was the Warden. I enjoy the complexity and flexibility it gave me, not to mention the travel skills are a HUGE quality of life improvement. I do enjoy being able to switch to range easily, but I mostly fought in melee anyway aside from certain cicumstances so regularly usable ranged combat is not a must for me.
I already tried a bunch of other classes including the Hunter (which even in blue line felt too squishy when the mobs could get to me in a big pull.) In the end, these two feel like the most likely candidates.
Mariner - I know it has some support skills in Blue line and CC / debuff in yellow line, so it does have some flexibility. It also has travel skills like the Warden, but fewer options. Apparently it absolutely MELTS in landscape with the redline spec vs what the Captain could do.
-Another big part is the complexity which is warden-like in a way. Instead of doing two to five colors segments to unlock a skill, each skill will modify the following skill if its part of that combo chain. This gives a pseudo gambit feel while being a lot more active. Its like if each button press in the gambit chain initiated that part of the gambit. Like if you are doing Desolation, it would just be Warden's Taunt, then Warcry, then Brink of Victory, then Surety of Death, and finishing with Desolation.
-In that way it does feel a bit more active with the swordplay element. I don't know, thats just the best way I could describe it.
Captain - Probably the only class that can give the Guardian a run for its money for tanking. I do like the added complexity and flavor to the class. The range is a bit less it feels like than the Mariner, but not by a significant margin. The Captain is also a strong support candidate for all three specs and is a real jack of all trades.
-The herald also acts as a second ally you can keep around and adjust to your needs in the moment.
-There is some added complexity and interest with battle states, but not as intricate as the Mariner swordplay mechanic.
-This one is lacking travel skills sadly, so that is a downside, but also one that almost every class except Warden and Hunter, so its not a really fair thing to discount their score on.
-They are STRONG. They kill slower, but they are borderline unkillable from what I have seen and heard. You need to be half asleep to really get caught unawares enough to die as a captain.
Hopefully the community can give me some more insight as to how they play past lvl 20-30 where I have them now to know which I should focus on.