Hi there -
The biggest problem that I find with your track is the timing of the sample attack on the strings / cellos. The sample attack is way too slow due to the quality of samples. If you adjusted the timing of the samples by bringing forward the stems (I presume you do use them rather than playing them back live) then the sample starts would not be so apparent. The brass also sounds a little unconvincing for this heroic / epic genre. It needs to sound BIG as this is a very very competitive market. IMHO.
Some examples of what I am trying to talk about:
https://audiojungle.net/item/epic-warlord/14873058
https://audiojungle.net/item/epic-battle-2/14780970