What are you going for? Research? Academia? Straight private practice? Combined cyto/general? There are lots of variables. If you are interested in cytopath as it relates to hematopath there are some programs (MD Anderson) which emphasize that a lot more. As with anything, if you are interested in academics I would open up major textbooks and see who writes the chapters (or the books). If you are interested in community practice there are lots of programs (most of them, probably) that will suit you and you should pick the program based on location.
The cytopath fellows at UCSF seem to get a lot of great experience and teaching (based on my one month cyto rotation and several months w/ the fellows at the county hospital). Of the graduating fellows last year, one went into academia and the other into private practice. Take that for what its worth (read: nothing).
As for the other ?, I would say first off do what you like doing. For me, cyto is very very tedious and not super intellectual. In addition, with Guardasil and universal HPV testing, Im not seeing much growth. Rads has also take breast FNAs--->breast cores. Cores are becoming more and more common. Hell, they are better than needles.
Would I do cyto? No. Is cyto useful right now? Yes, very.
For me the perfect 4 man group is:
1 Cyto boarded
1 Heme boarded
1 Derm boarded
1 GI fellowship trained