I bought my Nexus 5 until an expensive (~ 20) Case of Spigen (Neo Hybrid). This has also offered good protection has the Nexus 5 but simply made "great". This case is slim and serh is a good compromise between "no envelope is me too dangerous" and "what I buy as a sleek smartphone when it is in such a thick package". The fit is excellent. Most impressed me the structure of the material, which is slightly rough, extremely handy. Strongly reminiscent of the surface of the back of the One Plus One. The rough texture also fingerprints are passé.
The only drawback: This case does not last forever! In particular, the surface, especially at the corners is worn relatively "fast". My old has kept good 9 months. Since I use my cell phone but very often from the narrow pocket (usually jeans) out draw is the wear completely understandable. Due to the great structure (even if this does not last forever) and the slenderness get this envelope 5 Stars!