it depends on the user and what their preferences are. a good mechanical keyboard or good mebrane keyboard are both completely useable.
i will say that either a higher end membrane keyboard with quiet touch (soft press) keys or a mechanical keyboard are certainly head over heels better than some $5-10 keyboards with stiff membrane keys. quiet touch/soft touch is a huge improvement for typing speed as well as response time in games.
i have used a plethora of keyboards including...
$free with computer rubber dome boards (generally equal to $5 rubber dome below)
$5 rubber dome (missed keys when typing, more mispellings, slower reaction time in games, keys are hard on fingers/wrists and hands.)
$100+ rubber dome w/ soft touch (excellent gaming performance and typing speed. easy on fingers and hands)
$150 mechanical (again, excellent performance. i would rate them above domes for my own use)
i'm using a cheap $5 gearhead dome keyboard right now and it most certainly is a huge step down from what i was using before (a wasd cherry mx blue). however, its what i have to use for right now until i can get something better.
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my recommendation would be....
go with one of logitechs gaming or office keyboards with low profile soft touch keys or go with a cheap mechanical keyboard with mx brown switches and low profile keys.