I used to feel that Kodachrome 25 was the only color film I really liked, but then I realized as I moved up in format, other films that I didn't particularly like in 35mm became more attractive. ISO 25 films often require a tripod and aren't usually fast enough for subjects like wildlife requiring very long lenses that are only practical with 35mm, so in situations where I might be able to use such a film, there's no downside to using a bigger camera.

If you want fine grain, rich tonality, and high resolution in a color negative film, consider moving up to 6x7, and a film like Portra 160NC in medium format will end your nostalgia for Ektar 25.