The only green Unovan Pokemon that I actually cared for were Snivy and Axew lines. I guess just based on how much I used it, I'll go with Serperior as my favorite, since Haxorus isn't considered green by the Pokedex.
I know people have criticized it's poor design, movepool and all sorts of things, but really this is the most adorable thing on earth! Those cute little eyes and even though it may be based off a bag of garbage this thing and its evolution does wonders in competitive battling setting up spikes and hazards for the foe's team while also having some decent offensive moves. I used to hate it as well to be honest, but really Trubbish is great. :3