I started with 2005 series, it took 6 episodes to properly hook me, but I've loved it since then... it's worth sticking out S1 for the change to David Tennant (Tenth Dr). I've gone back and I appreciate Nine a lot more now, and there really is a lot of back story you'll miss if you skip the first series. Just remember that it's 20y.o and never had the budget that Star Trek did. Once you've fallen in love and caught up with the Doctor, go back to season 1 from 1963 😉