imac (mid 2007) - which OS to install?

It would be nice to have proper facts.

10.8.5 has an up to date Moziila based web browser called Waterfox.

It is at the same version as the current Mozilla Firefox.

Also, supports latest Adobe Flash Player

Current version of Firefox supports OS X 10.9 through macOS Sierra.

Also supports current Adobe Flash Player.

IMHO, older versions of the Mac OS run faster on older Macs.

Newer versions of the Mac OS (OS X 10.10, 10.11 and macOS Sierra) all need more than 4 GBs of RAM, now.

Gone are the days that Mac operating systems can run nominally on 2-4 GBs of RAM.

Very late answer : my 10 year old iMac runs smoothly for light tasks with El Capitan 10.11.6 with 6Gb RAM.

Don't expect much raw power !

Perfect for office work, light video editing and movies.

Excellent after 10 years.

DM

I have iMac 2007 2.4GHz and 4GB RAM, with Mac OS X 10.11.

Works fine. Speed is decent. Youtube videos play fine without stuttering. The UI is fairly clean (not cluttered). I like OS X 10.11 compared to earlier ones like Mac OS X 10.7, 10.6 down to Tiger 10.4. I skipped Mac OS X 10.8, 10.9 and 10.10 and just upgraded directly from 10.6.8 to 10.11.

Plus OS X 10.11 supports latest browsers from Google and Firefox so many websites work well with latest browsers.

Uh, yeah...

No.

Newer versions of OS X will barely, if at all, run on 2 GBs of RAM.

Newer Mac OSes need 8 GBs of RAM, now.

This is why all 2012 through current iMacs, some Macbook/Pros, iMac Pro, and some Mac Mini models all ship with a base RAM amount of 8 GBs of RAM, now.

8 GBs of RAM is REALLY what is needed for most current Mac operating systems.

A Mac running 10.10 through macOS Sierra, and, probably, macOS High Sierra ALL need 8 GBs of RAM now to operate at an acceptable/nominal performance level.

2 and 4 GBs of RAM are NOT going to back it any longer!

Good for you!

What do you do with your iMac?

Maybe fine for light tasks (email, web surfing, music, light photo/image editing)

Fine for minimal multitasking.

How does this iMac do with playing videos, streaming video?

Yes, I do light tasks as you listed above, which *most* users do.

Most (average) users will use their Macs for web surfing and email.

And yes, minimal multitasking.

And yes, I can play videos (eg, YouTube in HD just fine and in full screen with no stuttering.)

Your post essentially stated that you couldn't do anything or much of anything with just 4GB on OS X 10.11, and I'm here to say, YES, you can--for the average user scenario.

UPDATE: 10/24/2017

If you have an iMac (20-inch, Mid 2007) and are attempting to install a new OS please beware OS X El Capitan is the last OS supporting this Mid 2007 model. If you attempt to install and OS later than El Capitan you will receive an error as Apple has updated their File Structure in the new macOS High Sierra update. Save yourself some time and boot El Capitan onto a USB drive and save it. Good Luck !

See here: OS X El Capitan - Technical Specifications

Shows that OS X 10.11 just needs minimum of 2GB RAM.

My personal preference for you is to purchase a OS X 10.6 Snow Leopard install disc, then update to OS X 10.6.8 and STAY THERE!

Your IMac will run its best on OS X 10.6.8 Snow Leopard.

Mac OS X v10.6 Snow Leopard system requirements

Purchased Installer disc here.

http://store.apple.com/us/product/MC573Z/A/mac-os-x-106-snow-leopard

To install Snow Leopard for the first time, you must have a Mac with:

An Intel processor

An internal or external DVD drive, or DVD or CD Sharing

At least 1 GB of RAM (additional RAM is recommended)

A built-in display or a display connected to an Apple-supplied video card supported by your computer

At least 5 GB of disk space available, or 7 GB of disk space if you install the developer tools.

Later versions of OS X are more memory intensive and lean more towards being a hybrid of OS X and IOS.

The only other choice I do not really recommend, but your 2007 IMac may run okay on it is once your IMac is upgraded to OS X 10.6.8, purchase an email download code for OS X 10.8 Mountain Lion.

To install OS X 10.8 Mountain Lion, 10.9 Mavericks (currently unavailable) or OS X 10.10 Yosemite.you need one of these Macs:

OS X 10.8 Mountain Lion purchased emailed download code here.

http://store.apple.com/us/product/D6377Z/A/os-x-mountain-lion

iMac (Mid-2007 or later)

MacBook (13-inch Aluminum, Late 2008), (13-inch, Early 2009 or later)

MacBook Pro (13-inch, Mid-2009 or later),

MacBook Pro (15-inch or 17-inch, Mid/Late 2007 or later)

MacBook Air (Late 2008 or later)

Mac mini (Early 2009 or later)

Mac Pro (Early 2008 or later)

Xserve (Early 2009)

Your Mac also needs:

OS X Mountain Lion, Lion, or Snow Leopard v10.6.8 already installed

2 GB or more of memory (I strongly advise, at least, 4 GBs of RAM or more)

8 GB or more of available space

While there is the free OS X 10.10 Yosemite for immediate download on the Mac App Store, your iMac model will run a lot slower on this OS X version and is NOT without plenty of issues and really is not ready for use as an everyday OS.

My opinion here, stay away from installing OS X Yosemite for quite awhile.

iMac mid 2007 with 2.4 processor and 4gb ram will run El Capitan 10.11.6 nicely.

I applaud Apple for letting us poor people stay in the game for so very long.

I have a 24inch 2007 Imac, I am Running Mavericks , any OS above this and the computer craps out bad. Granted the computer is 10 years old and I eagerly await its death.

Uh.. Yes!

As I stated in my original post, I've got 4GB RAM running with Mac OS X 10.11 on iMac 2007 version. Runs just fine!

It's the same scenario for 2008 iMacs.

OS X 10.11 El Capitàn is the highest Mac OS for those models, too!