Welcome Tommy...
I had my Aortic valve replaced with an On-X valve. My surgery took place at the Cleveland Clinic and its my understanding that C.C. does more heart procedures than another other hospital in the U.S. My surgeon recommended the On-X valve to me and said that if he were having a valve replacement, he would want the On-X. This recommendation was due to the flow dynamics of the valve, he wasn't a supporter of the clinical trials where Coumadin is potentially replaced soley with baby aspirin. He told me that this valve is technically more difficult to install due to the high profile of the valve but he had done over 50 of them and was very confident. Its my understanding that there have been about 60,000 of these installed thus far. I think the St Jude is in the 500,000+ range.
If your happy with your surgeon and your surgeon thinks the St Jude is the best thing for you then run with it and don't look back. Confidence in the surgeon I think is key.
Im just over 5 weeks post-op and so far so good ! (knock knock) Honestly I think you will be happy with either valve type once its in and your recovered. Both seem to have great track records, seems to me the real test comes after your back to your normal life. Do you eat right, exercise, do the things necessary to help your body and not introduce risk factors you can control.
Best of luck, keep posting as we will all want to hear how you do through the process.