Prime's action scenes were a high-water mark, but I don't remember specific ones well enough to call out any in particular.
I don't mean to be rude but isn't that telling? I say that because I find Prime to be bland, visually flavourless, and generally not very memorable. I watched the whole series weekly when it was new, and have never felt compelled to revisit it. I've gone over my major issues enough times that I won't revisit them here, but I'll just say it's uninspired blandness aspiring to epicness without actually earning it.
Armada and Cybertron aren't prestige tv by any means. They each have their deep, deep issues. Still, I find both way more fun than Prime. Perhaps the most naval gazey and dull Transformers show put to tv.
I'm not an unbiased judge, but I say it still holds up in a lot of ways despite its datedness.
To each their own. I was confused by BM when it was new. I revisited it in my early 20s, the perfect time for me to appreciate its pseudo-intellectualism. I've since moved onto "ambitious show with some deep ideas it didn't really realize and maybe weren't right for the audience they wanted to reach... and it's just butt ugly."
The finale is probably one of the best parts but it's also... like... by that point I'm just tired of both of these schmucks and their pontificating.