Some very good advices here, especially from Cavalary and AB2012. Now my two cents, things that I personally (would) do. Disable hibernation, files indexing and swap file. I had no problems without swap file on Windows 7 for 6 years now. If, for any reasons you need it, then at least make it smaller than the default 1.5 x RAM size, and move it on a mechanical drive.
Now to the SSDs themselves, I'll be talking only about 2.5 inch SATA drives. Don't see too many valid reasons for the regular PC user/gamer to use M.2 SATA and NVMe drives. Sure the NVMe are much faster, but it's not noticeable in the usual everyday usage. I've seen a few tests between 2.5 inch SATA and NVMe drives, for loading times of different games, and the difference was only 1 or 2 seconds.
They also run hotter and are usually placed between the CPU and graphics card or under the graphics card, thus probably having an undesirable effect on the GPU's thermals.
First, look for drives with 5 years warranty, such as Samsung Pro and Evo, Intel, ADATA SU900 and XPG SX950U, Kingston UV500, Crucial MX500. Keep in mind that even good brands have not so good models, like Kingston A400 and WD Green. They are cheap for a reason.
There are some good brands, like Intel, WD/Sandisk and Crucial, that I would personally not buy SSDs from, because of their software/SSD tools, which is the bloated type, so I rather look elsewhere. My SSD brands of choice are limited to Samsung, ADATA, Kingston/HyperX and Plextor, but it depends on the model, of course.
For OS I would go with a 256 GB drive, in this order: Samsung Pro, Samsung Evo, ADATA SU900, Plextor M8VC, Kingston UV500, ADATA SU800.
Sometime this autumn, after AMD launches its CPUs, GPUs and chipsets, I'll build myself a system and on the storage side, I already have a Samsung Pro 256 GB, which will be for OS and some games. Another 1 TB SSD (exclusively for games), probably Samsung Evo, which started to get relatively cheap lately, or the ADATA SU800 (cheap, yet still good drive). And a mechanical drive for storage: WD Blue 2TB 5400 RPM. No need for 7200 RPM, I prefer it cool and quiet.
It would be wise to avoid the cheapest drives (vast majority are DRAM-less), especially those with the Phison S11 controller, like Kingston A400, Toshiba TR200, Patriot Burst, Patriot Spark, GOODRAM CX300, Palit UVS and many more. These are prone to failure quite often. I don't know if it's the controller at fault, or the fact that was designed as a cheap controller (one core as opposed to the previous quad-core Phison S10 or Samsung's MJX triple-core) and gets paired with cheap NAND memory modules.
For those interested, here is a
reddit thread with some good info (PDFs and spreadsheet).