The only thing I'd personally use JavaScript for is when it has to work inside a web browser, to be honest. I've been using LÖVE for awhile, but they took a few turns I do not really like...plus I hated the community. Now I use my own engine, so I never even heard of Solar2D.
Now what is important is what suits you best and the only advice I can give is try things out in both engines. Now I could not fully study it but Solar seems to instant testing what can make debugging faster. What I couldn't find about Solar is what OSes it supports. Having both Windows and Linux supported can be a good way to go. other than that it comes down to your programming style which you'll have to discover for yourself.