Although I find they concept of 'coins under 1$' to be shortsighted I get the appeal of finding A hidden gem taht still under $1 so you can load up on it.
$ price is just a small fraction of what makes a coin an interesting invest. They biggest point of interest for me would be good tech, tech that's not just a copy or clone of some other coin that address an actual demand in the real world. Since I believe there is a big market for the right platform, my money would be on XTRABYTES (XBY) a highly secure superfast codeagnostic platform that will solve the problems of scalability a lot of other platforms are facing. Another big market for crypto currencies would be the privacy coins. Since BTC has become almost mainstream and can hardly be called a privacy coin, the demand for a truly anonymous coin is ongoing. Here is where I believe Spectrecoin (XSPEC) can make a huge difference, They have successfully implemented TOR and OBFS4 and offer stealthstaking, which is pretty unique.
Both still way under 1$ and both still in full development with the potential of making a lot of profit.