For a single LCD monitor (excluding those used for advanced applications like medicine, oil exploration, etc.) the highest resolution would be 2560x1600. The only monitors with that resolution are 30-inch monitors.
There are 27-inch LCD monitors with a resolution of 2560x1440.
For 26-inch LCD monitors most would be 1920x1200 or 1920x1080.
For 23-24-inch LCD monitors most would be 1920x1080 a small number are 1920x1200.
Look for LED back-lit S-IPS panels as a first choice, LED back-lit S-PVA panels second, anything else last.