Let's see! Things I look for:
- Custom/interesting battle system. As in, no default front view, or even a minimal-customization side view setup. Whenever I'm scouting for RM games to kill time with, one of the first things I do is try to find screenshots or, better yet, video footage of the battle system. If it looks too default, I'm out. In contrast, if I see a good ATB/CTB setup with lots of custom, interesting skills that appear to be well-designed, as well-balanced party members, and nice-looking player battlers, there's a good chance I'll be giving it a go.
- Not using default Yanfly settings for everything. If I see fat HP gauges, I fully expect to see a bunch of other lazy default settings. Yanfly's plugins are super-customizable and a developer can do a lot with them. To me, seeing default on everything leads me to believe the plugins' probably aren't being used to their potential which, in turn, means the game is probably cutting corners.
- No default generator chibi battlers. I guess I'm just being superficial, but I find it hard to take a character seriously when their battle sprite is like 90% head. Doesn't matter how deep their backstory is, or how "cool" they might be. In battle, I just see a squat head with a tiny ant body attached.
- Good writing. RPGs are all about story, but how can a developer make that story interesting if their writing skills are terrible? I'm not trying to be down on people without decent writing skills, or people who don't speak the game's target language as their first language, but just like with graphics and coding, if a developer lacks that particular skill, they need to find someone who has it.
- Decent graphics. Now this doesn't necessarily mean "no RTP," contrary to what others here have said. I'm fine with RTP, but do try editing it a bit. For example, the default grass color is abysmal. The default swamp is...purple? While I'll obviously prefer custom graphics over RTP, but only if the custom graphics are actually good. If not, just use the RTP because it's not terrible. Just do something about those chibi battlers.