UPenn AMCS master VS UIowa AMCS PhD

[TrefoilZh]

Hey, you guys! Please help me out. 

Basically, I've got the two. One is from UPenn AMCS (Applied math and computational science) master without any financial aid and the other is from UIowa AMCS (the same)Ph.D. with 100% tuition covered and a TA with at least stipends $19,000 excluding summer vacation (I may get more stipends and I can expect my summer support also).

 

I don't know which one I should go to.Basically, I want to pursue a Ph.D. degree program and I've heard it's possible to switch to a Ph.D. degree program at UPenn AMCS. That said, I've got the reply from the graduate chair at UPenn. He told me it's ''unusual" and the decision is never made before the middle of the 2nd year of a master. So, is there anyone from UPenn AMCS could tell me the chance to switch to Ph.D.? I've read the requirements on websites carefully and I'm confident in passing the prelim exam at a Ph.D. standard. Also, please compare the two programs for me. I know UPenn has a big name as an Ivy league but what it really matters is the quality of the program. Of course, anyone and everyone are welcome! I'm awaiting your opinions!