What AI image generator do you recommend for scientific/educational illustrations?

I'm looking for an AI image generator that can create clear, accurate visuals for educational purposes—things like cell signalling pathways, GPCRs, molecular mechanisms, and other biomedical concepts.

I know AI-generated scientific content should always be verified against the literature, so I'm mainly interested in using it to create high-quality illustrations rather than as a source of scientific information.

So far I've tried Adobe Firefly and Luma AI. Both seem promising, but Firefly is only really good with the Pro plan. Once the credits run out, the image quality drops significantly.

Has anyone found a tool that works well for this type of scientific illustration? I'm happy to pay if the quality is consistently good.