There's a different skillset for being a good senator compared to an MP in the House of Reps. Members of the lower house, of course, have constituents to attend to -- a full-time job even before you tack on other roles like being a minister or shadow minister. But senators have a lot more committee work, and it's more important, because the government doesn't chair non-legislative committees, and chairs are expected to work a lot more collegiately. Effective senators are often the ones who work hard behind the scenes, and collaborate with senators from other parties to get outcomes that aren't necessarily confined to legislation.
The choice of best politician of 2017 was, ultimately, an easy one. It is Dean Smith who has effected a major, and thoroughly belated, change to Australia's marriage laws to end the discrimination that, until recently, both sides of politics supported. Other Liberal backbenchers played important roles in agitating for change, in this term of parliament and the previous one. Ministers like Christopher Pyne pushed the issue hard as well. But Dean Smith did the work. He put together a bill that addressed the issues identified in a near-unanimous (Eric Abetz was the only dissenter) senate committee report on the government's marriage plebiscite bill released last year. That was the bill he released when he and other marriage equality proponents in Liberal ranks again ignited the issue in August. It is the bill that, in substance, is the one that will become law.