Are people still running double MNK?
Generally speaking, most people don't run double anything, it's bad for loots and it's not necessarily good. Double monks run into massive TP issues, and the bard then has to sing TP song most of the time, making it rough on healers and reducing magic damage if you have a caster due to no time for foes. If you don't have a bard, then you're way fucked.
The typical setup at this point is like Monk/Ninja/Bard+ 4th. You can replace the Monk with a Dragoon, or even the Ninja, though that's not preferred. The 4th is generally SMN or BLM as you want some magic damage and you don't really want 3melees. Can be a 2nd bard too.
Monk+Ninja has a ton of synergy so it's a great combo, the Ninja can feed the Monk TP, which lets the bard sing whatever other people need rather than what the monk needs, and Ninja has Trick Attack which increases damage by a fair amount if it's synced to cooldowns popped+DoT reapplication in the group, since the DoTs will snapshot the 10% dmg increase on cast. For long dots like the monk dot or SMN dots with Contagion, that's a huge deal.
Bard is almost a given in any static, because of how useful the songs are especially when shit goes wrong. If you don't have mana song and one of your healer dies, it becomes insanely hard for the healer to be able to regen mana while still keeping people alive. The mana regen tools healers have are more for extending the time until they run out than actively gaining mana. Scholar can kinda do it if you don't lustrate, but well, you don't lustrate.
SMN and BLM tend to be fairly close. SMN does have a rez, but they also have mana issues so using rez can actually be detrimental in the long run and will nerf their damage by forcing them to energy drain over fester. BLM has issues maintaining high DPS on certain high movement fights, though with careful planning and knowledge of the encounter, it's possible to minimize movement a lot and only move during GCD or by using aetherial manipulation(which btw is fucking awesome).
Dragoons are probably the least desired class, they're a ton better now and actually do very competitive DPS and burst like crazy, while also having good aoe and very good TP management, but the problem is they have virutally no utility. It's hard to replace a Ninja or a Monk by a Dragoon because of that. You won't lose DPS, but you'll lose utility. That said, when making an endgame static, player skill is more relevant than class really, if you have a really good dragoon in your static he'll do more for the group than a shitty ninja or monk.