Shikamaru:
1. I can really relate to him - Just like me, Shika's a really smart guy, but is so lazy and apathetic that he doesn't mind what's going on around him because he just goes with the flow. He drifts through life like a cloud, and I can really see myself in that aspect of him.
2. He's got a really sharp, dry wit - One of the funniest characters in my opinion, Shikamaru states his mind and how he feels, and usually in a really snarky sort of way. He notices things not a lot of people notice, and can usually find some way to subtly point it out without actually drawing attention to it, and usually in a humourous manner. This wit is an extension of his brilliant intelligence.
3. Despite being a snarky lazy bum, he's fiercely loyal towards his friends - Shika's not the model inspiration, but he demonstrates that he cares as much as some of the more kinder characters several times throughout the series; in particular, his kindness towards Choji and never ceasing to believe in him, his friendship with Naruto and helping to break him out of his stupor after Jiraiya dies, and a more subtle one; his statement at the beginning of the Sasuke Retrieval Arc about how he'd give his life to bring Sasuke back despite not even liking him that much at all, all because he was a Leaf-Nin and Shikamaru's comrade. After the mission is declared a failure, Shikamaru breaks down in tears, not because he failed as a leader, but because his failure almost got his best friend and all his other teammates killed while he himself got out of it with merely a broken finger that he inflicted on himself. He also had a complete breakdown after Asuma died, before pulling himself together and becoming the first person in the series to single-handedly defeat an Akatsuki member, Hidan. He then promised to look after Asuma's child, pledging that to Kurenai.
So in summary, Shikamaru is pretty goddamn awesome.
