I'd joke around and say nothing, but even Symphogear has its things that annoy me, Just to name some

Too many redemptions
AXZ's not too good plot
Amalgam not being in the anime more
HibiMiku being forced
Injuries being ignored (not counting Hibiki's fusion)
(Continued as thread https://twitter.com/Torch_bb12/status/1283043659953340417

The mini arcs of Tsubasa
Daddy problems
OG3 getting too much hype
Serena not getting a official transformation
Kirika barely getting any past story farther than the FIS period
The main villains cheap goals to take over the world
Ver was alive in GX

Tsubasa being the only one who can switch to her gear from the previous season
Everyone not branching out to fight with others (main example is KiriShira)
Not enough moments from team Dango
No Kissing scene for HibiMiku
NO MOVIE YET? IT'S ONLY BEEN A YEAR SINCE IT ENDED BUT CMON

And.
(Ok people might kill me for this)
Miku really doesn't have much personality aside from the usual nice girl who is in love with the heroine. Her character was great in SZ and G, but it just kinda got annoyingly extra to me in the later seasons. But I still ship HibiMiku