I've seen both healer and tank for this, but I'm not sure which is most common. For the group activity finder for master fp's, which do you see most often?

By fundamentals I mean things not likely to change in upcoming patches. So nothing like which one has the most dps, or any other things tied to numerical values. What are the enduring qualities, or the design goals behind each class? Talking about mechanics over flavor. All 3 have their unique resource systems. Vanguards have the most ranged options. Shadows can stealth. Guardians...dunno. Site says they're melee tanks, but afaik, every tank's rotation make them all melee, so I'm not sure how that's special. That's all I could gather from my limited play experience. More info would be appreciated.

Need help from people experienced with the game in choosing a class. -Ranged dps is preferred role. Having others roles possible is fine, but the other bullet points will relate to rDPS role. - Instants yes, channels no, unless they're immune to interrupts like master strike. - Preferred lack of setup; prefer to charge in, guns blazing. - Ranged interrupt. Bonus points if they can get the cooldown for said interrupt reduced, like the sentinel or vanguard. - Ways to buff movement speed. Bonus if it works for the whole group. Not mandatory, but nice. - targeted abilities, like the mortar one for troopers are fun - Meter-lite. By this I mean not a lot of things one has to watch at one time, distracting from the fight at hand. DoT or HoT timers, etc. Doesn't have to match all, just the one you think matches them most. Detail is appreciated. Thanks in advance for any help you can give.

New player here, some questions: 1. Searched the forums, but couldn't find a recommended leveling build for sentinel. What do y'all recommend? 2. I chose sentinel mainly because their interrupt has the lowest CD in the game. For one, is that true? And two, does that matter? By that I mean, is there endgame pve content where that will be useful, or does everyone have enough interrupts regardless? Would putting two points in that talent be a good idea, or would it simply be wasting points that should've gone into dps talents instead?