90 William/88 Greenwich Club Residences

I looked at almost every building in FiDi, and 90 William struck me as by far the best value. (Or at least it was a month ago -- prices might have gone up since). The 1-bedrooms there are HUGE (larger than a lot of 2-bedroom apartments at other buildings), the finishings are great, and the price per square foot is better than any other comprable building. Plus they were more honest than most other buildings. (IE, they openly tell you the "worst case" pre-tax-abatment number of $420. The way the abatement program works, in the 2nd-10th year, that number will drop to 0 under the abatement, but you still have to pay the full amount the first year. This was the only condo I saw that was open about that fact -- everywhere else glossed over that and just said that taxes would be 0.)
If you haven't already, you should definitely schedule an appointment at this building to see if you like it.

88 Greenwich -- I almost bought there. My lawyer killed the deal (some dodgy stuff in the contract), but in retrospect, I'm glad he did. The finishes at 88 Greenwich are gorgeous, and the views are nice; but when you compare the price per square foot to any other building in the area, you realize the building is substantially more expensive, and for what? Keep in mind, also, that the nice views to the south are going away in 2-4 years. (The parking lot on the southern side of the building will likely be converted into high-rises sometime soon).

15 Broad - very bad finishings, low maint but expensive (stay away!)
59 John St - very good finishings but high maint (only a few available)
80 John St - good finishings and low maint and pretty good per sq ft value (only a few available)
90 William - not as good finishings but good per sq ft value especially for 1 BR