well, here is the story.
to a beginner, the real difference between a standard (membrane) keyboard and a mechanical kb, is that the mechanical will last much longer.
membrane keyboards wear out rather quickly, and the switches (the thing under the key) become hard to press; on the other hand, mechanical kb - which use Cherry Mx switches, and not membrane - last much, much longer - years.
now, cherry are not the only type of mechanical switch. all switches are mechanical in one way or another but normal membrane are not referred to as mech kb.
these switches have different feels to them; for example, the IBM Model M (now cloned by Unicomp) uses the Buckling Spring switch, which is considered the best switch ever made; they come in horrible gray or black, are bulky, and do not have lights / programmable keys.
they also are indestructible and provide by far the best key feel, but the switch is *slightly* heavy to type on... for some people.
cherry switches come in various weights (harder or softer to press) and the typing experience can vary somewhat depending on this; also, they can be clicky or not, and tactile (they have a "bump" when they actuate) or not. for example, Blue Cherry Mx switches have the classic tlak-tlak sound old computer keyboards used to make, kinda like a typewriter.
Topre switches are similar in feel to a brand new membrane keyboard, but will not "get old". Some people say these are the best - i have never used them - but boy are they expensive. Also some people complain that the feel is not as unique as cherry.
cherry and topre come in standard or tenkeyless (tkl), which means you do not have the numberpad at all. this is good for gamers because it gives you more room to move your mouse, while keeping a proper posture.
all mechanical keyboards are far superior in construction to membrane keyboards; metal plate base, heavier plastics.
so it's down to what switch you prefer, really. like you, i did not know what switch i wanted, and it's really hard to decide what feels best when you can't feel it first.
my suggestion is: buy one of each. 4real.
start with buying one of the unique ones, such as a cherry mx blue or mx green (the klak-klak ones), or a unicomp.
due to the way these switches are built, they are technically slower (we're talking milliseconds) than a "normal" switch so they might not be the best choice if you are a hardcore gamer, for example if you play FPS games.
however, these will certainly give you a great feeling when you use them and you will feel like you bought something unique.
going straight to topre you might not the money spent was worth the difference.
if you do play a ton of fps, like UT or quake, get a tkl with cherry Red switches. fastest actuation and least pressure to use, but sensitive to mistypes, so not good for DOTA and such. personally i play quake on a cherry mx clear (very hard to actuate, lots of pressure) and i had to get used to them, but now they feel fine.
oh btw, not only can you select the switch .. you can select the keycaps as well; generally, they will be either ABS (the classic plastic every normal keyboard is made of) or PBT, which is granier, harder, and feels like plastic used to feel in the 70s - the superior one.
so my recommendation is to buy something like this
https://mechanicalkeyboards.com/shop/index.php?l=product_detail&p=1501
made by Leopold (one of the best makes), its a tenkeyless with PBT keycaps and Cherry MX Blue switches. while you figure out what your ideal keyboard is, this one is guaranteed to make you go "wow", and all for a hundred bucks.