I think the best depends on what you primarily want to do. These are my main monitors:
Sony PVM-20M2U: Pure 15kHz RGB monitor. Outstanding for WHDLoad gaming. No ghosting or perceptible lag, like a 20" 1084 only much better.
Eizo L367: 15" TN LCD from mid-2000's era. This one connects to my A2000 with a Picasso IV. Despite its small size, this is the absolute best monitor I've used for a Workbench display on a non-emulated Amiga. 1024x768 is razor sharp perfection, due in part to the very high quality output of the PIV. The panel handles 50Hz just fine, so games look reasonably good thanks to plenty of adjustment range via the OSD (no banding), and vibrant colors with only minor smearing.
Iiyama VisionMaster Pro 17: Diamondtron CRT PC monitor from 1998. This one is connected to an A4000 also with a Picasso IV, and is simply the all-around nicest CRT I've ever used with any Amiga. Sharp text (for a CRT), nice color, both games and Workbench look phenomenal. I have the PIV programmed for a 75Hz PAL display, which gives an almost synced output for long-haul gaming, without burning your retinas at the default 50Hz.
I also have a small hoard of NOS CRTs, and keep a few 1084's around since they still come in handy from time to time. Keep in mind I live in the US, so it's a little harder to find a decent monitor thanks to no SCART and general lack of 50Hz capable displays.
