Dental student piping up, 'cause I just had to make this decision. This is lengthy, but if you're trying to decide, it might help!
Up until literally just last week, I used a 15" MB Pro since late 2008.
It is 6 years old. It still works. And it works pretty dang well--just as well as the new Lenovos and whatnot I have to use at work.
However, after 6 years, I figured it was finally about time to pick up something that was a little bit snappier and updated.
So my old computer has now been bequeathed to my father, and I have a new one.
First of all, I will never, ever go back to a PC unless I have to.
Macs just work. And they work for a long time, plain and simple. I have used multiple PCs before and they were ready to crap out after 2 years--almost unusable at that point. Ugh. No thank you. My friends who bought PCs for undergrad also had issues at the 2-3 year mark, which just stinks.
I ended up going with the 13" MB Pro. Here are the specs and price:
13-inch MacBook Pro with Retina Display
2.8 GHz Dual-core Intel Core i7
16GB 1600MHz DDR3L SDRAM
512GB Flash Storage
AppleCare Protection Plan
Cost with student discount:
$2,088 (computer) +
$183 (AppleCare).
Also, by using ShopDiscover to buy it, I got an additional 5% cash back.
It's an expensive computer, no doubt. However, to me, it is 100% worth it to have a computer that is A) awesome and B) will last forever. You're going to be using your computer for ~4 hours a day for the next 4 years. You want something that holds up.
I didn't go with the Air, although they are sweet computers.
First of all, the 13" Air is ONLY half a pound lighter than the 13" MB Pro. In your hand, the difference is almost completely unnoticeable. An 11", in my opinion, is just too small. I was fine to make the switch from 15"-->13" because the 15" was a bit bulky, but I won't go 11".
Also, you can just really beef up the MB Pro a lot more than you can the Air. I keep stressing longevity, and the better your computer is when you buy it, the greater the chance it has of staying applicable as new programs are developed. I loaded out my 15" back when I bought it 6 years ago, and I think that's a big reason why it's still working so well today.
The only spec I didn't increase on my Pro was upgrading the memory to 1 TB. I bought a Toshiba external drive to do that... It cost $80 bucks that way instead of $400.
I'm not sure how CPU-intensive (for lack of a better term) the programs will be that I have to use in dental school, but I wanted to make sure I had something that could handle them all with ease.
On to battery life... Granted, I have only been using my computer for a week. However, my brother has a 13" Air, and I have been able to compare mine to it. His gets a *little bit* more battery life, but not by much.
Quite frankly, when are you ever going to really need to use your computer for any longer than 9 hours without having access to a charger?
The longest I have used mine consecutively is 6 hours. I got home from work at 5 PM and browsed the Internet/watched Youtube videos until 11 PM. I had the brightness up pretty high. When I closed it down for the night, I still had 4.5 hours of battery remaining. If I hadn't been watching so many videos or had the brightness down a few notches, it would have been even more! I was majorly impressed.
Oh, and I have also installed Windows 8 on my Pro. It cost ~$130 to get the Windows operating system, and BootCamp comes pre-installed. It is running flawlessly. (Windows 8, btw, is STRANGE. Haha!) I will have to use this for a few programs at dental school. I'll probably end up using Parallels, but I won't buy it until after Yosemite is released.
I also have Office for Windows installed.
When I bought my computer, I picked up an extra charging cord. Yeah, it's pretty steep at 80 bucks... but it is SO NICE to be able to leave one cord at your home desk and not have to roll it up every time you want to take your computer somewhere!
I'm sure I'm leaving some stuff out, but seriously, this is an amazing computer. I recommend it 100%. Please feel free to ask any questions, and I'd be more than happy to comment!
Edit to Add: The Retina display is just stunning, too. Since I study all of my notes from my laptop, I want something that is as easy on my eyes as can be.