Palit are genuine, yes. Some manufacturer's have better QC, or better customer service etc - but any genuine GPU manufacturer is partnered with nVidia and will provide a solid product. Palit, Zotac, Galax etc are smaller players so don't have the market reputation, but you'll get a genuine product running at the listed speeds/performance etc.
There a couple of completely unknown brands, selling GPUs way below market price - usually based in China (I forget their names, but you usually find them on eBay). Those are the only 'brands' you should avoid, because they are usually older card models with a custom BIOS to report as another model.
If there's not a whole lot of difference in price, the Gaming series (generally) are a...