Is it unusual for a prospective university to offer a bonus to your stipend after visiting? I am a prospective PhD math student. This year's application season has brought me down to two schools to choose from: 


Medium-sized department, ranked &lt;80 on US News (whatever that means), very welcoming people, potential advisor is very young but seemed like we would "click", surrounding area and city is beautiful, program looks awesome. 
Larger department, top 20 program, potential advisor is famous in his field, current advisor says I would work well with him/he's a cool guy, don't know much else since I've not visited. 


I am waitlisted at university 2. University 1's initial offer to me included the standard stipend along with a decent fellowship. I made a visit to university 1 and talked with many professors and my potential advisor. After this visit, they offered me a ~17% increase in my stipend due to some professors advocating for me who were apparently impressed (whom I do not know other than my visit). I feel that this is a good sign, but I am ultimately pursuing a career in academia. So I know prestige plays a big roll in future jobs. Assuming I have an offer from university 2 as well:

Questions: 


Is this late stipend increase offer typical? 
Based on your experience and insight in the job market for academics, which university is the better option? 


Thanks for your time to read.
It's not too unusual. Lower-ranked schools know they need to work a little harder to attract top talent. For example, I did an REU at a lower-ranked school, and they admitted that the only reason they bothered offering an REU program was hoping that some of us would become grad students -- they normally couldn't attract grad students of our caliber. Offering a 15% stipend increase to particularly promising students seems altogether appropriate.
University 2. I might seriously consider university 1 if you didn't like university 2 for some reason -- what you do is far more important than where you go, and getting into a top school does not guarantee you an academic future (not even close!!). But in your case, both seem like good options, so if you get into university 2, I would go there.