Being a young cigar novice, I've only had two ISOMs so far (I've got about 6 or 7 sitting in my humi, but they look so pretty laying in there that I'm always reluctant to smoke them)
The Cohiba Siglo III is about a corona size and is a great smoke, very VERY full-bodied, but never harsh or bitter, always smooth and creamy. I believe most of the Siglo series is available in little cardboard 3-packs that have big, ugly Surgeon General-style warnings on them.
The San Cristobal de la Habana in the El Morro size is another good smoke. It's more of a medium-flavor, and might be a little tight. Mine had a plug near the tip, but I just massaged between my thumb and forefinger and it loosened up and the draw improved considerably.