Macbook Pro new HD Specs?

I would go for an SSD if you can. Much faster than a HDD and a much better experience overall. But if you need a HDD, anything by Samsung and Western Digital are great. I would get 7200 RPM, but a 5400 one is good enough too. Anyway, a HDD cannot even saturate SATA 1 (I believe), so SATA 2 or 3 is pointless. Get the most cache you can find, but 32 is good. Physical size depends on your computer, but most should be 2.5". If not, then it will be 3.5".

 

Solid-State. The performance boost you will get will be outstanding.

Your MacBook Pro supports SATA II, but SATA III is backwards compatible at a negotiated speed of 3Gb/s.

Edit: You will want a 2.5" HDD, or SSD.

 

Get a 9.5mm 2.5in HDD, preferably 7200rpm.
I have a 1TB HDD @5400rpm and it works flawless.

I really suggest getting an SSD.
Since your 2010 model only supports SATAII, get a cheap one like Crucial M4.