Making good sprites is not necessarily tied to what program you use. It's your graphics design skills that do most of the work so keep on practicing! The program can provide you with tools to complement your own skillset but you still need a good foundation to take full advantage of those tools. Alternatively you can search for free assets or purchase assets from various asset stores.
The program I personally use when I draw sprites is paint.NET, it's very simple to use so I recommend it if you're new to drawing sprites. minimal amounts of potentially confusing features and a very easy interface that is fast to learn, very reminiscent of WinPaint.