So a couple things before I give my opinions on the specifics of those classes/jobs.

1 - Consider tanking. Tanks are in short supply and high demand, and Paladins are very easy to play. They are a semi-high pressure job, but it is uncomplicated to use. If you don't think you will have large chunks of time to devote to queuing for dungeons, waiting to get into a group, then doing the dungeons without baby interruptions, being a tank will help you get instant queues for almost anything you want to do.

2 - Try everything! Some of the classes in this game function pretty different from one another, and from other MMOs in terms of traditional playing styles. I would recommend giving everything a try until you find something that you enjoy!

As for those classes/jobs:

Thaumaturge/Black Mage - VERY easy to play. The first 15 levels are kind of boring and a little tedious because if your low health pool, but they end up being rediculously fun (1800-2000 dmg crits, and the best AoE dmg spell in the game!). They attack from range, so there is a slight advantage there, but they have low health pools, and 90% of their damage dealing ability requires you to stay still to cast a spell, so as you dodge red circles and AE effects, you will lose some DPS. Overall, it is my 3rd favorite class in the game. In terms of simplicity, it is, in my opinion, the simplest lvl 50 DPS class to play, in that you can maximize your damage through a very simple rotation that doesn't require much innovation or circumstantial changes (i81 BLM).

Archer/Bard - I don't have any personal experience with ARC/BRD past level 15, but it is one of the most in-demand (if not THE MOST) DPS classes in the game at level 50. They have great group utility, and they do decent damage. They are also the most flexible in terms of damage up-time, as they don't ever have to cast spells, so they can be constantly moving and dodging. In terms of simple mechanics, they have a lot of buttons to press, but nothing overly complicated to deal with.

Lancer/Dragoon - OMG I hate Dragoon, lol. But the reason I hate it is because is slow and very simple compared to MNK (my main). You have one main damage combination, a couple DoTs, and a lot of off-GCD abilities. I will say that they do pace the skills you get pretty well for DRG. Meaning it will start off as being BEYOND simple to use your skills, and then they add one or two every 5 levels that you learn to weave into your rotations. My DRG is only level 34 because I didn't like it very much, but I got the general gist of where the class was going from there.

Overall, I'd recommend trying some of every flavor before you put a ton of time and effort into one class.