What MIDI instrument combinations sound good?

[Firebolt391d]

After some personal research, I have come to see a few different main ideas:

1.) The usage of multiple instruments depends on the song and situation that is required. Some combinations of OS  instruments may sound good in one song, but bad in another;
2.) The octave number/height on the "register" also plays a key role in many instrument combinations. For some instruments, if the key is too high, it does not seem to work well;
3.) Mainly, from my own research notes, it seems that more prominent and bold-sounding instruments (such as Smooth Synth, Scifi, and Bass) seem to go with other instruments better.

Here are some common instrument combinations (2 instruments only) that I found to be interesting...
-Acoustic Guitar/Electric Piano
-Smooth Synth/Electric Piano
-Smooth Synth/Electric Guitar
-Smooth Synth/Violin
-Smooth Synth/Cello
-Smooth Synth/Scifi
-Scifi/Electric Piano
-Scifi/Acoustic Guitar
-Scifi/Electric Guitar
-Scifi/Cello
-Synth Pluck/Epiano
-Smooth Synth/Acoustic Guitar
-Bass/Acoustic Guitar
-Bass/Electric Guitar
-Cello/Acoustic Guitar

-Trombone/FrenchHorn
-Violin/Cello

-8bit_Sine/8bit Sawtooth
-8bit Triangle/Acoustic Guitar
-8bit Triangle/Electric Guitar
-8bit SawTooth/Trombone
-8bit Triangle/8bit Sawtooth

A few of these, such as the Violin/Cello, created what almost sounded like a completely new sound altogether.
The rest of them mainly sounded just like the two sounds playing together, both of them mutually strengthening one another. Synth Pluck and Smooth Synth sounds oftentimes blend in such a way as to make an echo effect that continues even after it's companion's note has already died out.

I would encourage you to try around on your own though!
This list were some of my favorites - after combining  of all of the instruments and listening to each dual pair of instruments, these were my *personal* favorites!

This list also only includes 2 instruments paired together. I would also encourage you to test around with more than 2 instrument voices!
Good luck, and I hope this helps!