3DMark
3DMark is the latest version of this hugely-popular synthetic benchmark. Making use of DX11 features such as tessellation, compute shaders and multi-threading, it provides modern-day results and is available as a free download.
We're starting to see a definitive divide between the GTX 950s that are heavily overclocked and those that aren't. The Palit and PNY cards fall into the latter category and are priced accordingly. This is a tightly contested area of the market, with plenty of choice in the £130-£150 bracket.