For what it's worth here goes (some I haven't seen in a while):
I came in series three but in retro was impressed by Denise and Ian's QS. I too think Jill's jive was a tad over-rated but saw her FT live and rather liked it.
Zoe and Ian's tango (yes this is what we used to get when people did tangoes to proper music instead of rock numbers) and samba
Also watched James and Cam's tango and it was harbriger of the best damn showdance - Cam doing her own thing chereographically and it being bonkers and fab.
Series four:
the pocket rockets - Louisa and Vincent's jive
wasn't that impressed with Emma Bunton generally but did love her tango
and of course no list is complete without Matt and Karen's salsa and AT - the originals and probably still the best
Series five:
Matt and Flavia - salsa the only reason the word probably is in the statement above
John and Nicole - salsa - a very close runner up to both of the previous efforts - man that man had rhythm
Gethin and Cam - waltz - if he was a painter this would be an old master
Alesha and Matt - FT - I liked this more than their waltz actually - and even more impressive is that it was essentially improvised
Series six:
Austin's jive and paso - objectively they prob aren't the best but someone I once knew (who was kinda of a pain in the bum apart from that) had a cool icon with a hourglass that said 'attempting to give a damn' which was followed by a dialogue box that said 'failed - damn not given'. This is how I feel about Len's crit of the later - I don't care if there have been better pasos and he looked like waiter handing out canapes it was effing fabulous.
Cherie and Rachel's rhumbas - both different, both awesome and both in the opinion of someone who normally hates rhumbas.
Tomilla showdance - the best example we've even seen. Seen it performed live had to endure Tom's attempt at being a judge to do, still totally worth it.
Series seven -
I do have a bit of a weekness for the Cola charleston - it's fun. Vincent and Nat's QS was pretty good too.
Series eight;
Scott and Nat's jive - because sometimes if a dance is chereographed by a genius a prop is an asset.
Kartem charleston - got no love from the judges - proof sometimes they don't know what they're talking about IMO - my fav of their dances.
Series nine;
Chelsee and Pasha's (Pan-Am) QS - I can't believe that this isn't getting more love on here. Harry was more consistence but this is one of the reasons why I wish Chelsee's nerves (and a rubbish showdance) hadn't thrown it away for her in the final.
Jason and Kristina's tango - the campest tango in the world and one of the most enjoyable.
Harry and Ailona QS - class in a glass.
Holly and Artem - paso -
Series ten:
Louis and Flavia tango - yes ok Louis aces it dressed as a zombie but still great.
Denise and James charleston - whatever you think of them - this was pretty darn good.
Dani and Vincent - VW - God I miss Vincent's chereography - my husband finds VW's as dull and ditchwater and he loved this now 'That's Amore'.
Series eleven:
Abbey and Al waltz - I did really like Abbey and found her over-rated however even I have to admit that this was very special as was
Natalie and Artem's - VW.
And from the sublime to - Mark and Iveta - CCC - I am so glad that other people put this one down because I'm glad I'm not the only person who loved the ridiculous genius that was this. Saw the live show with Abbey, Nat and others from that series and Nicky and Karen's charleston (which I revised my opinion of and recognised for the greatness it is) but this was still the highlight for me although seeing everyone waltzing and tangoing was great too.
Series twelve:
Pixie and Trent FT - Mostly I'm with Monkseal and foxtrots bore me but this one managed to be both innovative whilst still traditional enough to keep Len happy.
Caroline and Pasha charleston.
Series thirteen:
Jaoilana jive - well duh! although their little red riding hood AS was pretty darn good too.
Helen and Ali - samba - take your mummy out - yes sometimes even the most bonkers themes can work brilliantly in the right hands. Thank you maggie for reminding me of that
So far:
Darren and Oti's QS
Ore and Joanna's AS and jive