anyone of those will work fine. they are very simple devices. always see people whining about how evil the company who make the FT232R is, but it's their right to update their driver to protect their work. if you got one of those, be smarter and get the older driver instead, and you will be fine. CH340G is a very capable chip, but again, there are people complaining about its low cost, no reset line, and driver problem, but it's quite the opposite. A single Ch340G chip is slightly more expensive than the whole usb-ttl converter. how ridiculous is that? they don't include the reset line because it doesn't work on some boards. and most functions of the Ch340G are unused anyway. An USB to TTL converter really only needs Tx, Rx and gnd pin.