Film Composer shopping for a 27" monitor $300 budget

Hello,

I am a film composer (who also plays Team Fortress 2) in the market for a 27" LED monitor that is reliable with good components, has the best color for the price and has seamless response time. I often score really fast action sequences, play Team Fortress 2 and use my monitor to watch movies. I

I am not considering a television because computer monitors seem to have better components and last longer.

I am currently using a late 2007 Imac and I am terrified of somehow downgrading my monitor and getting the wrong thing.

The monitor will be used with my hackintosh with a decent video card, i7, 3.5 ghz processor and running IOS off a OCZ Vertex 4 SSD with 32 gigs of ram.

How would this new monitor compare to my late 2007 Imac's monitor?

Thank you in advance.

Best,
Travis