Alrighty, since I did my peds rotation at Christ, and we also rotate thru lutheran...
I think if you want to do Cards, I've actually heard GREAT things about Cardiology at Lutheran. Christ does have the best surgeon around (Ilbawi- I know you're not kidding!), but I've heard the rotation at Lutheran is better- you learn more, and they have a great cards program too. I did Peds Endo at Christ, and LOVED it- great attending, who loves teaching and will let you do anything. I'd highly recommend heme-onc, though. The attendings are amazing, you'll work hard but you'll get to know more of the residents and have experiences both inpatient and outpatient. The other two I'd recommend at Christ are either GI or Pulm with Dr. Akhter. Both attendings are (to my understanding) a little more influential in residency selection. Although, if I had my choice, I'd do heme/onc at Christ.
Hope this helps... good luck!