As noone else has bitten I'll have a go. I tend to play pretty casually but then I'm guessing if you were a uber l33t bunny hopping type you'd probably know the answer already.

I think mag is probably the way to go right now, if only because we've all been running round on stam toons spamming dswing-dawnbreaker-execute for so long that it's just nice to have a change. As to which, well....

Magplars are pretty firmly on top right now to the point that they're ahead of the other classes by some margin. They got a bunch of buffs in back in u30 which really moved them up the ladder then another big buff to backlash in u31.Those changes have given them incredible survivability with stuff htd and living dark and then the full package on offense. I mean, you've got a gap closer which stuns and sets off balance, easy pressure with jabs which ofc also heal you, and a huge amount of quite bursty follow up damage from stuff like crescent sweep, purifying light and the burning light passive. Plus a nice execute in the jesus beam. On top of that, they're the easiest class to play bar none. You really can't go wrong with them.

I don't think I'm seeing anything in the pts notes that's going to challenge their dominance. If anything they're getting a slight buff - javelin's damage will now bypass block.

DKs on the other hand are in a much better place after U32 but people tend to overstate how much they've improved. Most of the changes zos made - stuff like combustion, charged, battle roar - were to sort out their godawful sustain, but they still have the most expensive skills in the game. And the rest was in the nice to have category - stacks on whip last a bit longer, foo gives you 3 fireballs rather than two, eruption is a cost over time... They didn't get anything like the big changes to healing power / damage numbers that temps got. My sense is that they're much better than they were and definitely a good choice but not really in the same league...

The changes on PTS are interesting; it looks like the damage boost from engulfing flames is getting a nerf, while the heal from burning embers is getting turned into a hot rather than a burst heal. I think that will reduce their overall damage while giving them slightly better - or at least more consistent - healing, but it looks more on the margins. Not sure it will make big changes but we'll see.

There are two other things it's worth noting. First, one of the things you'll find about DKs is that the class kit misses quite a bit. Whereas you could literally roll a templar and take it for a spin, the DK lacks quite a bit out of the box. To even compete with a temp on healing you'll need restoration staff, to get any mobility you'll need psyjic, for defense you'll need vampire 3 and ideally mistform... And ofc you'll still lack stuff they have like a decent gap closer, an execute...

Second, an awful lot of the Dk's offense comes from dots. I suspect one of the things that's making them seem more potent at the moment is that fact that there's so much plaguebreak around that people can't / won't purge. At some pt tho zos is going to nerf that, and if people start purging again it's quite a hard counter to DKs.

In short, I think templars are quite a long way ahead of other classes and much stronger out of the box. DKs, you're going to need to grind out some stuff to make them good, and they're still not going to be quite as good as a templar. On the other other hand, yeah, templars are pretty easy to play and jabs can get seriously old after a while. I'd give Dk's a definite win on visuals and the fun factor. But YMMW. Personally, I'd roll up a templar - much easier to get going - and see how you go. You could always go to DK if / when you get bored of it or work one up when you don't fancy pvping. Whereas if you roll up a DK and don't like it, you'll have had to invest a lot more up front.