For photo editing response time isn't that important, generally S-IPS panels are considered to be best for photo editing due to good colour accuracy and viewing angles, with S-PVA panels second best and TN Film panels not really recommended for colour accurate work.
IPS panels tend to be very expensive, PVA panels reasonable, and TN film the cheapest. You can check what type of panel a monitor uses and
read up on the different types at
www.tftcentral.co.uk.
Dave