What performances stick in your mind as 'the performance of the series' for you? I didn't watch Series 1, so unfortunately I can't comment on it. For me:

Series 2: Kyran and Melanie's Billie Jean routine
Series 3: Chris and Frankie's The Time Warp routine
Series 4: Todd and Susie's Help! routine
Series 5: Daniella and Matthew's The Look routine (Jai Ho was a bit too over-hyped imo)
Series 6: For me it's a toss-up between Laura and Colin's It's All Coming Back To Me Now or You Can't Stop The Beat, and Sam and Brianne's Riverdance.

What were your series-defining performances?

Danny Youngs routine to Rocky always impressed me, Maybe because he was topless

I can't remember the early stuff but I recall Kyran's chasing cars being the performance that stood out rather than billie jean.

Me too!

Series 1. Stefan and Kristina - Mr.Bojangles
Series 2. Clare and Andrei - Since you've been gone
Series 3. Suzanne and Matt - Music and the flying routine
Series 4. Ray and Maria - Spoilt for choice but I'll go for Nothings gonna stop us now.
Series 5. Hayley and Dan Jai Ho
Series 6. Laura and Colin - Spoilt for choice but maybe the ultimate skills test; Stop

Can't wait to see what Laura and Colin deliver in the final.

Oh, and I forgot to mention Suzanne and Matt's Time To Say Goodbye as a stand-out performance in my OP

Can I be greedy and have two or three for each.

Series 1- can't remember anything really from it.
Series 2- Clare Since you been gone or Kyran Chasing Cars or the props one.
Series 3- Suzanne Music or Chris Cry Me a River
Series 4- Todd Help
Series 5- Danniella The Look Jai Ho 2nd found it a bit overrated tbh.
Series 6- Laura erm I'm so excited or Stop with It's All Coming Back to me now and the Last Dance just behind.

Series 1 = Stefan & Kristina Mr Bojangles
Series 2 = Kyran & Mel Chasing Cars. Their props routine to Hello Goodbye & Billie Jean were also amazing & loved Clare & Andrei's Since U Been Gone too.
Series 3 = Again very difficult to pick 1. Suzanne & Matt Music & Fame were brilliant as was Chris & Frankie's Time Warp, Cry Me A River & Living La Vida Loca.
Series 4 = Ray & Maria's Rock Around The Clock.
Series 5 = Will say Jai Ho for the impact at the time although I'm bored of it now.
Series 6 = Laura & Colin's Hairspray & Stop routines and Vanilla Ice & Katie skating to Ice Ice Baby was a classic moment.

Series 1 Stefan's Mr Bojangles/ John's Black Horse and the Cherry Tree
Series 2 Kyran's Chasing Cars/ Claire's Wishing and Hoping
Series 3 Suzanne's Music/ Chris' Time Warp
Series 4 Anything Ray and Maria did
Series 5 Danniella's chair routine (Jai Ho too overhyped for me as too much pick dancing/ carying/ frantic arm movements whilst standing still)
Series 6 Chloe's Kiss Kiss/ Sam's Riverdance

Series 1 - Stefan's 'Mr Bojangles' and John's 'Amerillo'
Series 2 - Kyran's 'Billie Jean' and Clare's 'Since you've been gone'
Series 3 - Chris' 'Cry me a river' and Suzanne's 'Music'
Series 4 - Ray's 'Nothing's gonna stop us' and 'Rock around the Clock'
Series 5 - Hayley's 'Jai Ho!' and Daniella's 60's routine (I can't remember the name, but she wore orange)
Series 6 - Laura's 'It's all coming back to me now', 'Last Dance' and Sam's 'Riverdance'