So far, it sounds awesome overall! I have a couple suggestions though. During the first buildup, the piano seemed a little weak, and was quickly overpowered when you introduced the reverby stab synth sound. Not sure if that's what you were going for, but it could have a bit more presence. Also, during the first drop, the layered synths were interfering with the hi hats/crashes, and they sounded a bit lost in the mix. Doing a bit of subtractive eq'ing to the synths around the main frequencies of where the hi-hats and crashes lay should help bring them out a bit more in the mix. Also, like what has already been suggested, the kick needs some attention, and the bass in the section at 2:11 should be boosted up a bit too. An idea for the transition, since you mentioned you'd like to add in a guitar, would be to add either a crunchy, slightly distorted or a clean reverby guitar riff into the section at 2:11 and have it carry into your next drop. If you don't have an actual guitar, Ample Sound has some pretty neat sample based guitar vsts that you could check out, which are pretty expressive and have a nice sound to them. If you're familiar with Aire, he's been using their AME2 plugin and the results have sounded fairly
nice.