I dont think its really fair to designate one woman as the best ever or a man as the best ever because
there are so many things that should be taken in consideration.
There have been so many changes on the show over the years,in some series they were a plethora of good dancers(serie 5) whereas in others not so much(this serie and serie1).So I dont think its fair for all celebs who took part in this show to choose only one person as the best ever.
For the females, I would say Kara and Alesha are probably on the same level.However, Rachel and Lisa were both really good but they didnt put a lot of emotion in their routines just my opinion and were not really popular with the public.
I think that if Chelsee had the same amount of time as Kara and Alesha she would have been probably be even better than Kara yes I said it


.
Alesha and Kara were not working during their time on strictly and they had all the time to rehearse as many times as they could,Chelsee didnt have that luxury.
For the amount of tough choreography she was given week after week for a limited amount of time, I would rate Chelsee above Kara/Alesha I know many will disagree with me but its my opinion
.
For the men once again its tough to pick one.I would rate Matt Baker above Harry.Colin was very good and Mark also.So top 3 for men will be Mark,Colin, Harry.
Alesha:foxtrot
Kara;rumba
Chelsee:Paso(A-M-A-Z-I-N-G)
Mark:Tango(not AT)
Matt B:Salsa(hello hip actions
Matt Di Rumba
Colin QS
Harry:VW He is sublime in ballroom dances