How much improved are the new Macbooks versus old Macbooks? Will I regret purchasing old hardware?

[neoelectronaut]

I'm trying to make a decision between a upgraded Macbook Air versus a low-end Macbook Pro and it's frankly making my head spin a bit.

My only real requirement is that I'd like 512GB of internal storage. I'm moving from a 1TB HDD on my iMac and while I think I can probably squeeze into 512GB, 256GB is more than likely a definite no-go.

Ideally I'd like 16GB of RAM, but most of my options are limited to 8GB, so I'll stick to 8GB across the range.

As far as processors go...ideally I'd like the fastest they offer, but the truth of the matter is that I'm happily still using a 2010 27" iMac which is on an i3, so even the low-end Macbooks are faster than what I'm using now. I'm only upgrading out of convenience...I'm trying to simplify my belongings and the smaller footprint of a notebook computer is going to be a nice switch from the hulking behemoth I'm using now.

Here's what I can get for my cash. These are obviously all pre-tax and don't include Applecare (Which I'll likely pickup sometime during my first year of ownership.) I won't be including graphics into my specs below because I won't be doing any gaming and I'm not quite pro enough to use any GPU-accelerated tasks in Photoshop.

12" Macbook:

• 1.2Ghz Intel Core m5
• 8GB RAM
• 512GB SSD
• $1599

Refurb 13" Macbook Air:

• 1.6Ghz Intel Core i5
• 8GB RAM
• 512GB SSD
• $1189

13" Macbook Air:

• 1.6Ghz Intel Core i5
• 8GB RAM
• 512GB SSD
• $1399

Refurb "Old" 13" Macbook Pro:

• 2.9Ghz Intel Core i5
• 8GB RAM
• 512GB SSD
• $1439

"Old" 13" Macbook Pro:

• 2.7Ghz Intel Core i5
• 8GB RAM
• 512GB SSD
• $1699

Refurb "Old" 13" Macbook Pro:

• 2.9Ghz Intel Core i5
• 16GB RAM
• 512GB SSD
• $1609

"New" 13" Macbook Pro

• 2.0Ghz Intel Core i5
• 8GB RAM
• 512GB SSD
• $1699

The 13" Macbook Air seems to be the way to go, right? I can even throw in the Intel Core i7 processor upgrade and only get up to $1549, even less than the 12" Macbook price.

I'm aware that the Macbook Air doesn't have the "Retina" screen, but I've always felt that the Retina screen feature has been mostly marketing. The existing displays I use both at home and at work are plenty high resolution for my needs, so that's more or less a non-factor to me.

I'm also aware that the New Macbook Pro is sporting a new generation of processor, and "Gigahertz" doesn't mean anything, just as it hasn't for the last decade or so. Still, the Macbook Air seems like the best bang for the buck.

So I turn to you, MacRumors users, for guidance.

Any thoughts on the matter?

Edit: I tend to forget that Refurbished hardware is an option, let's roll that in for good measure.