I have a planck at work and a preonic at home. It takes some time to get used to but now that I have switched I will never go back. I might try something split like a corne next but I'm kind of waiting for something that matches my olkb boards a bit better.
Ortholinear would be the new standard if I had my way. I'm also eyeing that MNT Reform pocket pretty hard for that awesome keyboard but I really want them to release a tactile switch option for it.
Olkb.com can probably answer most questions you have. They where one of the first to bring ortholinear keyboards to the market. Planck and Preonic are models they make. Preonic has a number row, planck doesn't. MNT is a company making open and hackable devices like laptops, they aren't making devices for the masses, instead trying to make something that is longer lasting and repairable. Their 'pocket' model has an ortholinear keyboard built in, and I just think that's neat.
I use a planck as my daily driver. I wouldn't recommend it unless you have some good reasons to switch.
It took about 2 weeks of use and practice before I could type at a reasonable rate with it. And then it took about 2 weeks before I could type on a normal keyboard again.
I had a few reasons why I got one
I travel enough that having a small form factor was important
I have small hands, and was developing some wrist pain from stretching and moving my hand on larger keyboards. It did help a lot, but I think switching to a 60% would have been just as helpful.
I didn't type that fast anyway and have pretty bad form, I was hoping switching layouts would be a natural way to retrain my typing and type faster. I did improve for a bit, but I stopped practicing and am a pretty terrible typer again
I do think it's pretty cool. It's a conversation starter when people walk by my desk. The planck is a 40%, so most people haven't seen a keyboard that small.
At work I use a planck paired with a numpad. It's perfect for me, but it was definitely a learning experience. Probably 2 weeks or so to get used to it. Most people would probably like a preonic more, the number row is a must for gaming and it makes learning quicker.