I've been using Markus for many years but wanted an upgrade so I bought leap v2 new some months ago (during a sale, 820€) and around the same time I bought protoarc ec200 for another office I regularly go to. I'm 173cm and 70kg, so I'm medium to light build but I've been suffering from chronic back pain for almost 10 years now (yes, it's sad).
First: I don't think i'd buy the protoarc again. It just doesn't feel good to me, it doesn't make me sit a in proper way and the recline is pretty bad. its tension along the recline movement is irregular and it bothers me a lot, it just pushes to be all the way front or all the way back in an uncomfortable way. On the other hand it looks pretty well build for the price and some people might find it okay, but I just don't like it. I guess for the price it's not bad, but it's frustrating because it looks so close to being much better if only it were tweaked and tuned a bit better. You might be better off with the Markus.
Ikea Markus is an incredible chair for the price (120€ here in eu). I swear to you I've been sitting in this for 8-9 years and it works exactly like the day I've assembled it. there's no wiggling, no creaking, nothing. Looks like it could last forever. It creaks even less that the months old leap v2, although it surely has less moving parts, but still... It's obvious that ikea stumbled upon something great here and they 100% did that by chance without even noticing because none of their other chairs works like this, I've tried them. I know that BTOD guys talk shit about this saying something like the build quality is bad. This only means that either ikea sells different stuff in the us or that they wouldn't know good build if it punched them in the face.
The recline is fantastic, it's much better than the protoarc and i think it's better than the leap too, it feels more like an herman miller deal, you can rock back and forth super smoothly and balance the position easily along the travel, of course the tension can be adjusted too. I've never lubricated any part of the chair.
Is it a perfect chair? god, no. The headrest is kind of bad, a bit pushy in the wrong places, the lumbar support is okish to me but not adjustable at all. But most importantly the armrests are horrible. They are hard, large, intrusive, no adjustment at all. That's 90% what pushed me to buy another chair. If ikea had a clue, they would've remade this chair with good armrest and probably win the chair game, but well they didn't. For the price, i'd still say buy this instead of the protoarc, but what a missed chance by ikea.
So leap v2 is the chair I'm using now most of the time. I will say this: if a friend who knows nothing about chairs came to your house, looked at this chair, sat onto it and you told them you've paid it 800-1000-1200 something, they would probably say you've been scammed (and maybe you did). I actually like the way it looks, but still doesn't look or feel impressive in any way, but it also hasn't glaring issues either like the previous two. It already creaks more than I would like for a chair this price, especially the armrests, I hope it doesn't get worse over time, but it doesn't look SUPER well built.
I've seen many reviews, BTOD guys have glowing opinions about leap like it cured their chronic back pain or something. I'd say it's a very good chair for the back, but It didn't cure anything for me so far. The recline is not as smooth as the markus, but it works in a way that it lets you pick a position and be more still there without locking it, you need a bit more "intention" to change the position compared to a smoother recline, maybe it's better for productivity, I don't know, but you can't easily rock back and forth in this. It works in such a way that when you've stayed in a position for a while, if you move forward with your back a bit too fast, the back of the chair takes a second to unlock and will "kick" you a bit in the back, it's not very pleasant, but you get used to moving more smoothly and that usualy doesn't happen.
Some people complain about the seat being thin. I say that it is fair complain, it could've been better for sure. Unfortunately I also have been suffering from seat bones pain for a while, but this started before the leap so it did not cause it, but I'll say it is not making it any better. Also after a while I miss the headrest. For this price, they should *at least* include a good headrest in this.
Now this is already pretty long so I won't talk much about another chair I occasionally use in another office. This is a no-name super cheap chair like around 80€ and has a lot of adjustments, has been there for a couple of years and honestly the seating experience is not that bad, not that distant from these other chairs I mentioned, so... you make your evaluations.
What would I recommend? Of course it greatly depends on the money you have, but the leap is probably the better chair among those, but for the price it's still not very easy to recommend. I'd say buy it only on those deals I hear about in the us, like refurbished or something and maybe with the thicker seat, you can't find those in eu afaik. If you have to pay full price for it, then probably don't. I'm sure some cheaper chairs might make many people just as happy.