So both Lindsay and Sharna have had 4 T4 contestants and 3 T3 contestants without a win. For those seasons, their contestants' ranking in average judge scores:
Lindsay - 6th, 3rd, 3rd, 6th
Sharna - 5th, 2nd, 5th, 2nd
So I suppose Sharna has had better partners. I wonder if one or both will get an Obvious Contender next season, as I personally hadn't ever heard of either of their partners this season.