Coffee

Depends on what you're looking for. Do you want drip? Espresso? French press? Manual ? Electric? What's your budget?

For cheap/low quality electric grinders, most of them are blade grinders: they chop up the beans in very rough sizes, take forever, sound like they're gonna explode and make terrible coffee. Don't bother, they're shit.

Burr grinders come in 2 main "cutting technologies", conical and flat. Conicals are mostly found on manual grinders, entry level electrics and some medium to high end ones. Flats are much more common on the medium to high end range because they tend to need much more torque and therefore powerful motors. As for the differences between the topologies, it mostly comes down to particle size distribution and the effects it has. Conicals tend to emphasize texture (think thick, syrupy espresso), flats tend to emphasize clarity (flavors tend to be more easily to discern). But they exist in a continuum and burr shape alone is definitely not the only factor.

As for actual recommendations, take a look at James Hoffman's and Lance Hedrick's channels on youtube, they have a lot of incredible advice on all kinds of grinders, among other coffee equipment. Be warned though, it's a very deep rabbit hole :D

My main grinder is a DF64/G-Iota (~400€), and is an absolute workhorse. It's a mid-range grinder that can be very easily modded to rival grinders more than twice its price, takes standard 64mm flat burrs and can be upgraded with super expensive SSP burrs. I love it. I think the current generation corrected many flaws I had to mod out of mine.

My travel grinder is a conical manual 1-ZPresso J-Max (~150€) that's so quick it can grind at espresso range at almost 1g/s, with excellent results.