The polynomial I have, pKw = 4471/K -6.0875 +0.01706*K says that it hits 14 at K = 279.99 (24.8 °C). That's a bit warm for lab/room temperature (76.7 °F). My concept of room temperature is more like 20 °C and I believe that ASHRAE's defintition. I have noticed, however, that when you check into a hotel room anywhere else in the world the thermostat seems most likely to be set for 21 °C.
I have always used 20 °C unless I have special reason not to and that is probably because the ASBC Plato table is for 20°C/20°C specific gravities. Plus the pK values one typically sees for carbonic acid match 20°C (but are very little different for 25°C).
If you look up sucrose on Wikipedia it gives the solubilty at 25 °C but ICUMSA defines the standard sucrose soultion at 20 °C and all its formulae (for density and refractive index) are Taylor series expansions around 20 °C. OIML's ethanol formula is also expanded around 20 °C. Anton Paar's densitometers ship set for 20 °C. etc. If you look in the CRC Handbook you'll find lots of SG data referenced to 25°C and lots to 20°C and some to lower temperatures. Glacial acetic acid is called glacial because in the days it was named laboratory temperature was closer to 17 °C than 20 (I guess scientists were more rugged then). Also, referring again to electrical engineering, noise figure calculations are referenced to 290 K (17°C) supporting the idea that lab temperature was 17 °C years back.
My impression of all this is that in the middle of the 20th century 25°C became the 'standard' temperature but that more recently it has fallen back to 20 as almost everything coming out these days seems to be based on that number.