Im starting this thread because one of my coworkers (Amy Dumas aka : LITA) thinks Kim clijsters is the better baseliner, but i argue shes only better at retrieving but Jen is the harder baseliner, tennis power wise.
If i had to choose, or you for that matter, the bigger more hard hitting woman, id go with Jennifer, she has all the groundstroke weapons to be a really good baseliner, but if i wanted to go for quikness and defense, Kim by the edge, shes a tad faster and she always gets those hard balls back, forcing you to hit another winner.
You should look at movement, pace on the ball, groundstroke weapons (forhand, backhand) technique, agility, indurance, depth of the ball, and placement. Serve is not a factor and recent results shouldnt influence your decision, this is talent only please. Please stay as un-biased as possible, id say they are pretty equal...but Jens the heavyer hitter.