Late to the party, but here goes:
1st rehearsal:
Austria: Good voice, boring performance (looks stiff), ok song. I like the colors.
Estonia: Another bland song and boring performance.
Slovenia: The performance was better than the previous two. I like that they seem to be moving around on stage and that Hannah is interacting with the dancers.
Croatia: I love the colors and lightning here! This is the first time I hear this song and I quite like it. I'm not sure I like the way they are interacting with each other on stage. It looks fake.
Denmark: I hate orange

. Ugh, I hate it when the singer(s) don't move around on stage. She needs to work the camera more! She looked uninterested.
Russia: This left me with absolutely no impressions. Are those things on stage balloons or light bulbs?
Ukraine: Lovely colors. Love the dress. That's about it.
The Netherlands: Zzzzzzz. Good voice, but Zzzzzz. How did this get 46% of the votes?!
Montenegro: Haha, what?
Belgium: Average ESC-performance. Didn't really stand out in any way.
Belarus: Yay, prop! Did I mention that I hate orange? Because I do.
Moldova: Wow, that's more like it! This is a ballad I can enjoy. Interesting show, nice backdrop and I love the colors and lightning.
Ireland: I hate the backdrop. It looks like Ryan is having fun on stage and the song makes me smile. Love the dancers

.
Cyprus: Oh no, another ballad where pretty much nothing happens on stage.
Lithuania: Purple is my favourite color

.
Serbia: Alright.
My top 3:
1. Moldova
2. Denmark
3. Croatia
Will make it to the final:
To the artists: Interact with the camera! Don't just stand there! I based my comments on the first rehearsal so the final performance might look different (I hope so).