The Windows Spectrum Emulator is the one i personally use, not because the other emulators are rubbish because they are certainly not, but because it was the first one i used since becoming interested in emulation and i suppose it's just what you get used to.

Installation	Click on wspecem.exe and you are away
Ease Of Use	I personally think this emulator is extremely easy to use, just click FILE then click OPEN and then click on the game of your choice
Compatibility	This emulator is capable of running over 6,000 emulated games - which should be more than enough for the avid Spectrum fans out there. Will run all formats TAP, Z80, SNA etc
Graphics	The graphics are near perfect to a real spectrum with no glitches or errors
Sound	The sound is also near perfect without a crackle or pop in sight. Sound can either come through your PC speaker or through your sound card
Speed	Game speed on this emulator is adjustable
Registration	The beauty of emulation is that most authors create these superb programs in their free time and therefore expect nothing in return. WSPECEM does not have a registration fee and is 100% free.
Download	Get it here