Tbh I like all cards but my favorites are :
Illustrated postcards like watercolor botanicals, cozy cafés, bookstores, gardens, and little neighborhoods.
Authentic travel cards that show everyday life rather than famous landmarks: local markets, side streets, fishing harbors, old train stations, tiny post offices.
Japanese stationery aesthetics: soft colors, thoughtful design, a little whimsical without being overly cute.
Botanical subjects like wildflowers, strawberries, mushrooms, pollinators, seed packets, and cottage gardens.
I also love it when there are beautiful stamps, a few thoughtfully placed stickers or decorative washi tape, and a handwritten message - those are what I try to do on my cards I send out!
But honestly anything you love to send and write makes me happy!