Free agency in WNBA will be fascinating this year--could be a lot of moving pieces that change the needs of each team (Though the Liberty could stand for as much help as they can get). As of right now, Collier makes the most sense for NYL's needs (should she leave early), but after that, it's about as clear as mud.
Thinking about the rosters as they stand, what does each team need the most:
NYL: First, they need a healthy Ionescu and Durr, who along with Kia Nurse and Jazmine Jones could make for a very young, dynamic backcourt (with Clarendon providing veteran support). But the forward and center positions could all do for a significant upgrade offensively, and I can't remember the last time NY has had a great small forward.
DAL: Like NY, their guard situation is in a pretty good place. Arike is Arike, Gray has established herself as a very solid pro, and both Harris and Mabrey showed promise (and if MoJeff ever gets healthy, that's even more PG depth). Sabally is a future star at the 3, and Thorton will give you solid minutes at the forward spots. But they don't have any posts worthy of a true WNBA contender.
ATL: Again, like the previous two teams, their guard situation as it stands now is pretty stacked. Carter is a future all star, Laney made a huge jump last year, Courtney Williams remains a very good pro SG, and they should get Tiffany Hayes back this upcoming year. That leaves the post again as the biggest hole in the lineup--E. Williams and Monique Billings are both better than avg rebounders and defenders, but neither of them has much of an offensive game outside 5 feet. That doesn't cut it at the 4-spot anymore, and unless Glory Johnson is able to recapture her form from a few years ago, they need an upgrade here.
IND: Unlike the other three teams, IND should be decent in post between McCowan, Dupree, Cox (if she makes a big jump her 2nd year), Achonwa, and Lavender (should she return). And with Allemand and the return of Wheeler at PG, and the Mitchells at the 2, backcourt is decent. Alas, Indiana has not had a true offensive option at the 3 since Catchings retired (ironically, had they kept Laney last season it could have been her).
So in short, the biggest need for the lottery teams seems to be at the forward/center spot, which does not seem particularly deep at all in this draft class as this moment. Trades/free agency will be important.