YoungProdigy, I listened to your music and I think you can make it sound better with the same samples!
You need to focus more on the realism of the orchestration. In a lot of your tracks your orchestra sounds unbalanced, and a lot of the things you write will not even sound good with a real orchestra. That's why you often get "the samples sound unrealistic".
The first thing you need to do is to balance your template, and the way you do it is by performing a real score (a score that you actually own, where you can read all the dynamics and articulations) in your DAW and then by balancing all the tracks in order to make the ensemble sound like the real recording of that score. That way writing unbalanced things in your template will be almost impossible and this will teach you how to orchestrate.
Try to perform all the parts yourself, do not quantize anything, and if you can, don't even use a click track. This will help with the realism.
Another tip I can give you is to transcribe transcribe and transcribe! Listen, try to reproduce what your favorite composers do and then get yourself the score, look at it and compare it with your work. You will learn tons of things!
After that just create a little bit more space in your template with reverb, and use EQ and compression when you need to.
Here's a mock up of the Galaxy Quest Theme (Written by David Newman) I did a while ago using only samples from Kontakt 5 and a free sample library called the Total Composure Orchestra. You will hear that even bad samples can sound okay when you apply those techniques :
https://soundcloud.com/claude-ruelle/galaxy-quest-mockup
Today I use better sample for sure, but it's only 20% of what will make your music sound better. The other 80% reside on what I told you above.
Hope you are getting my point. You write some pretty good music, and you're only a few steps away from getting it to sound amazing!
Happy composing! :)
Claude.