Poland

Every major operator (Plus, Orange, T-Mobile, Play, Cyfrowy Polsat) uses GSM900, GSM1800, UTMS900, UMTS2100 and FDD LTE1800 bands (the last one isn't ready right now on some networks, but by the time Neo900 is out it should be operational everywhere). In next years FDD LTE800 should also be available, but AFAIK it's not known yet which operators will win the permissions for needed frequencies.

Therefore, the best options for Neo900 user from Poland are:

• PLS8-E - works at every band mentioned above, including LTE1800 and LTE800
• PHS8-E - works at every non-LTE band (obviously, as it doesn't support LTE )
• PHS8-P/J/K - the same as PHS8-E
• PXS8 - the same as PHS8-E and PHS8-P/J/K, with additional CDMA2000 support on 800/1900MHz. While there are some CDMA networks like Centertel, I'm not aware of any consumer-grade CDMA service in Poland, so PXS8 is probably not worth it when one wants to use Neo900 mostly in Poland.

The non-optimal, but somehow working option:

• PLS8-US - despite general support for UMTS and LTE, it supports only GSM900 and GSM1800 from bands used in Poland, so it's limited to 2G there

Not working at all:

• PHS8-US/USA

Supplement:
Some people may be interested in support for Aero2 BDI (free internet service). Aero2 BDI operates on UMTS900 and (soon?) TDD LTE2600. While UMTS900 is supported by PLS8-E, PHS8-E, PHS8-P/J/K and PXS8, TDD LTE2600 is not supported by any offered variant (PLS8 supports only FDD bands). So, Aero2 BDI should work on Neo900, but not on its LTE network that's currently in development (so just like almost any device out there, as TDD LTE2600 is used almost nowhere ).

Main source: https://www.uke.gov.pl/pozwolenia-ra...oraz-cdma-4145 - however, lists here contain all permissions for operating BTSes, so some of them might not be operational yet (or maybe even at all). While for GSM/UMTS it's doesn't seem to be problem, for LTE it is, as only small part of allowed stations are actually in use and there's a lot of inter-roaming between companies and networks, so I tried to validate it all with press releases and news notes about LTE deployments.

ODS source for table: http://neo900.org/stuff/bands-poland.ods