>>>Hi,
>>>I am being asked to develop an application to run on a Windows tablet running Windows 8 or Windows 10 Professional.
>>>I guess I can install SQL Express, but would like to use the version with the smallest footprint. Can anyone tell me what that would be? SQL Server Compact? LocalDB? Something else?
>>
>>SQL Compact has the smallest footprint by far. But I would probably try to go with SQL Server 2008 R2, because it gives you a full SQL Server with SP, advanced tools etc, but that depends on your needs. In any case using SQL Server 2008 would mean your solution is easily scalable.
>>
>>SQL Server 2008 R2 requires 512 MB RAM, SQL Server 2010 requires already 4GB RAM.
>>
>>Here the requirements for SQL 2008 R2:
>>
>>Supported Operating System
>>Windows 7, Windows Server 2003, Windows Server 2008, Windows Server 2008 R2, Windows Vista, Windows XP
>>
>>System Memory:
>>Minimum 512 MB for SQL Server Express with Tools, and SQL Server Express with Advanced Services and 4 GB for Reporting Services that installs with SQL Server Express with Advanced Services
>>
>>Hard Disk:
>>2.2 GB of Disk Space
>>
>>Processors:
>>X86:
>>Pentium III-compatible processor or faster (Processor Speed - 1.0 GHz or faster)
>>
>>X64:
>>Minimum: AMD Opteron, AMD Athlon 64, Intel Xeon with Intel EM64T support, Intel Pentium IV with EM64T support (Processor Speed - 1.0 GHz or faster)
>>
>>IA64:
>>Itanium processor or faster (Processor Speed - 1.0 GHz or faster)
>>Limitations : SQL Server Express supports 1 physical processor, 1 GB memory, and 10 GB storage
>
>Thanks, I'll consider that but the tablets will be running Windows 8 or 10. Will that be a problem with running 2008 R2?
>The compact might just work as I won't need to be doing any database maintenance on the tablets (hopefully)

I am running SQL 2008 R2 on windows 10 for a long time already. It also works for Windows 8.1.
You must use Service Pack 2 though (of SQL Server). However you could go straight to SP3. Here is a good list of SQL versions and releases:

https://sqlserverbuilds.blogspot.de/

Answer from Microsoft:
SQL Server 2008 R2 requires Service Pack 2 to be compatible with Windows 8.1. For more information, please read the following support article:

http://support.microsoft.com/kb/2681562/en-us