I really like Resolve Reviews and I tend to side with him more than any other reviewer. He seems to favor treble more than me, and enjoys bass less than I do, but as he states he mainly listens to jazz, classical, and acoustic so that all checks out. I’ve heard both the Meze Rai Penta and the Campfire Solaris, and I think he is pretty much right about both. I think the Pentas sound better than the 99 Classics, but not as refined as the Empyreans. In general though pretty true to Meze’s house sound. Pretty unusual compared to most iems I’ve heard, so I may have liked them mostly for standing out. My friend sold me his Andromedas to upgrade to the Solaris. I’ve had a chance to listen to it a decent amount, but I personally prefer the fit and sound of the Andromedas. I do think the Solaris is a little more capable though, and the bass is probably a little better. I’m not really an iem guy, and the Andromedas are the only one I’ve heard that I’ve liked from the first listen. I’ve forced myself to get used to some others, but the Andromedas will likely be my first and only expensive iem purchase
I think the Andro’s are sort of a bench mark when it comes to how a good iem should perform sound wise, this goes for build quality too 
For me it’s fit first while retaining that sound. I’m much more picky with iems than headphones so its exaggerated. I also may prefer silicone to foam, and thats a big part of the Andro sound for me