I am, and will probably always be a Doctor/Rose shipper so: Season 2!

And series 5 and 4.

4 rulllllsssssssssss come'on i mean dona is one of the best butt there is better

whos better?

I love all seasons, but a little bit more the tenth Doctor, because it is very well performed by the great, handsome David Tennant. Catherine Tate gave as Donna Noble a ´kick´, a special touch. Do you know, what do I mean?

In order of preference:
Series 2;
Series 4;
Series 3;
Series 1;
Series 5;
Series 6.

I hated Series 6-I only enjoyed 'The Impossible Astronaut', 'Day of the Moon' and 'The Girl Who Waited'. :(

My Favourites go as...

5: Series 6 + Series 2
4: Series 5
3: Series 1
2: Series 3
1: Series 4

Let's just get one thing clear I'm judging the series' one thier episodes and story arcs. Not because of favourite characters.
In my eyes, Series 1 had three bad episodes - Aliens of London, The Long Game & Boom Town. Series 2 had four bad episodes - New Earth, The Idiot's Lantern, Love and Monsters & Fear Her. Series 3 - which I really enjoyed had a bad two parter, Daleks in Manhatten & Evolution of the Daleks. Series 4 - I'm not gonna lie, enjoy watching every episode. Series 5, The Beast Below, Victory of the Daleks and The Lodger were the bad eggs for me. And series 6 - well, I enjoyed the arc, but I didn't enjoy episodes 3, 5, 6 & 12.

Series 4 hands down

Donna and her grandfather were the best things to happen to New Who

She didn't treat her mother like dirt like Rose
She didn't pine after him like Martha

Series 2 was the most overrated series ever: too many shitty stories like Fear Her, Love and Monsters, and way too many meh stories like Tooth and Claw. The only good episodes were the two parters, School Reunion (SARAH JANE SMITH), AND The Girl In The Fireplace (which BTW was written by STEPHEN MOFFAT)

I loved every episode of series 4, clear of The Unicorn and the Wasp (which wasn't terrible, just kind of meh) , which was still better than Love and Monsters and Fear Her.