Returning player trying to pick a tank

[TouchandFeel]

If you want a more straight-forward rotation, Gunbreaker or Paladin are the way to go. They both have an easy to grasp pattern for their rotations that logically just flows together with PLD following a physical damage phase under Fight or Flight into a shorter magical phase under Requiescat, while GNB has regular 30s mini burst windows with their Gnashing Fang + Continuation combo, their full burst phase every 60s with the No Mercy buff plus Bow Shock and Sonic Break, and of course a little extra oomph every 90s due to Bloodfest.

Of the two, I'd say that PLD is probably the most straight-forward while GNB feels a little more "actiony" with a lot of fast button presses during their burst periods.

Also, if you have taken DRK to lvl.70, not a whole lot changes with how it plays, at least not in single-target/boss scenarios. You basically just get the second part of your AoE combo, stronger versions of your Edge/Flood abilities and Living Shadow which is on a 120s recast, so not something you will be using constantly.

DRK's aesthetics are definitely cool, my personal favorite of the tanks, but their game-play style is definitely not going to be for everyone.
Some people are turned off by the more resource and priority focused game-play of jobs like DRK and WAR, feeling that it just doesn't feel consistently busy enough or is too "fractured", while other may dislike the more rigid structure of the rotations for PLD and GNB.
It's all about trying things out and seeing what feels good to you.

However, I will say that if you really like the aesthetics for DRK compared to the other tanks, it may be worth sticking with it. It may not be clicking just yet, but putting in a bit of time with it at higher levels could bring it all together for you and you could end up liking it, you just needed some "breaking in" time. Also never discount how much an aesthetic that really speaks to you can elevate a character and just make everything seem or feel cooler.

If you are not overly attached to the aesthetic and you could roll with whatever style, then it's definitely worth checking out the other tanks too. Who knows, maybe you'll end up liking more than one of the tanks and end up leveling and playing two or more of them or go full omni-tank and level and play all of them.