I like both Tarja and Anette, but maybe Anette is a bit more of my taste. Especially after listening to Imaginaerum I've thought Tuomas made the right choice.
I love the old albums too and I've listened to them countless of times, but I still feel Anette's different voice is quite refreshing. Tarja would've left the band anyway even if the boys didn't kick her out.
Although no one can know 100% sure what happened between them, I'm more on the boys' side. When I was 16 or 17 I had missed the chance to get their autographs during a festival. The queue was cut right in front of me and I was quite down because of it. But later I met them in front of a hotel by accident. At first I didn't even realize I was standing so near to them. I was just staring with my mouth open. But when some other people started to gather around them I ran there too.
When Tarja noticed us she quickly walked in and didn't look back, but the boys stayed outside and started to share autographs. I gave my brand new Once album's lyric booklet to Tuomas. He signed it, smiled and gave it back into my trembling hands. I thanked him while almost crying. Then I started to scream and jump around like a maniac. Haha I hope he doesn't remember that. My brains tend to temporarily stop functioning when I meet my idols.