Yeah that's the thing about Orthros no Inu (the more I talk about it, the more I want to rewatch it...), he's not entirely good...well I don't want to spoil. Personnally, I watched Last Friend and then after that Orthros no Inu (because his acting in Last Friend put me in a Ryo marathon, I needed to watch all his dramas^^) and both those dramas are in my favorites, but Orthros is still better for me.
In Last friends, there is no actual story I'd say, it's just : you have those people, they are different, see how they interact with each other. Love, hate, friendship, violence, etc. And all this brings a story, because the actors are just that good. There isn't just one male and one female lead and the other bystanding, all the characters are important.
In Orthros no Inu, you have a story : something happenned, and two people who are apparently really different are involved. You have in the same time a confrontation between moral good and evil, a search for truth, and a strange kind of bond between the characters. The two male leads are just amazing actors and it's also part of the drama's beauty.
And I can't say in which drama Ryo acts best, because in my point of view both the characters are perfectly portrayed. In Last Friends, you want to believe that there is good in him, and in Orthros, sometimes you can see the darkness inside that kind person.
