I currently own a HP S700 boot ssd. While my HP s700 is from a well known brand and is able to boot my pc to windows 10 in about 20-25 seconds, the 120gb capacity is cramped and the ssd is still much slower than a quality drive like a mx500 or 860 evo.
120gb capacity drives arent filled at first after installing windows, but they fill up quickly. If you install programs onto a hard drive like I do, the installer has to put some files on your ssd. 250gb ssd is a minimum as a boot drive.
My kingston sa400 240gb game drive is a lot faster than the HP S700 and the 240 capacity is much more suitable for windows. The kingstons performance is a fair bit behind a mx500 or 860 evo, but for a game drive where i just need decent speed and dont store valuable data, the kingston is fine.
I would suggest buying at least a 240 or 256 gb ssd. If you are going on a budget you could buy a kingston sa400 240gb ssd, but if you can squeeze a 256gb mx500 or 860 evo in budget, i would advise you to go that route.
Don't trust your overall system responsiveness and your data to a cheap, no name drive. Quality drives only cost the price of a nice dinner out and bring higher quality, better longevity, and faster speed to your system.