Hmm...good question.
I have an older US Games "greenie" with dark green borders and it has the best colors of any Thoth deck I've seen to date. It's the first one I grab if I want to get a good clear look at some detail. Despite the green borders and green tinge to some of the cards, the image clarity is perfect. I got lucky when I found it. I wasn't looking for it, but I walked into a shop one day and there it was so I bought it. I see it on eBay from time to time, but as the green shading can vary from light to dark, and since sellers frequently don't post good pictures, it can be hard to really know what you're looking at. This might be one you will just have to watch out for.
In the meantime, a lot of people rave about the large AG Muller blue box "B" seen
here. I haven't actually seen it so I can't say for sure. I have seen the same version that is sold by US Games (on Tarot Garden's chart it's just called "Green Box"), and personally, I didn't like it. The colors were overly saturated and didn't look very good. It could have just been that particular deck though, as print runs can vary in quality.
Happy hunting!