BRD is definitely not the answer here. Keeping up with your songs and each of their buffs along with your oGCDs, triggered effects, procs sometimes, not other times, support abilities, etc. It is not easy and a mediocre BRD is worse than a bad DNC or MCH.

MCH is probably the easiest DPS in the game, in my opinion, followed up by DNC, both of which are ranged and do not have cast bars. I don't think the abilities themselves are what make a class easy or hard, but the circumstances in which you can continue using them. Cast bars in general make a class harder by default because there are mechanics that make you.... move. And if you are learning, you will not know how to efficiently cast without being in circles. We may find it easy, but a new player may not. Melee also makes a class harder, because you have a very limited range to actually do things, and must manage that range (and possibly positionals) which can often require more fight knowledge than being at range.

BRD was my first dps back in 2.x because it was easier then than now, even.

I find SAM to be rather easy but it is incredibly structured and sort of based more around completing a specific order of abilities in a tight timeframe where mistakes punish you by costing you further time in trying to recover from it (ie, not getting a seal by accidentally not completing a combo).

MCH is the meme streamer choice since you can have medium/high dps relative to everyone else with minimal effort. DNC is easy but you have to pay attention to the procs and know how to use your support abilities effectively.

Overall, I really think MCH is the easiest. I use MCH for farming mats and just about nothing else, because it's hecking boring to play.