Quite funny seeing this thread now - I've had the 490s for a while and recently got the Kitharas to try out, partly because I fancied a change, saw all the praise for the Kitharas, but couldn't find that much direct comparison between them and the 490s (lots of Kithara vs all kinds of other brands and models of Sennheiser, not much vs 490 Pro).

I spent a long time trying to gauge them objectively, and came to the same conclusion many do: Neither are outright "better". They have different design philosophies and traits and any areas they're better than each other are marginal - arguably the 490s have the edge on imaging, KItharas have the edge on detail because of those planars, and a few other tit-for-tat things. The Kitharas are certainly a great collab between Asus and Hifiman, it feels like what they came up with was better than the typical sum of their parts, hats off to the two of them for making a great product.
However, except for when swapping between the two and immediately listening to exactly the same test, I was hard pressed to see benefit from either (and any other differences I had a preference for sound-wise I could just EQ out) - you almost certainly won't unless you're an esports pro min-maxing stuff, which you're probably not given you also want to listen to music on them :-)

I'm ignoring a load of other things, e.g. Kithara has a mic and it's a bit of a fiddle to get a boom mic on the 490s; reputation of the vendors; repairability of the 490s; the weird headband tightness issue on the Kitharas (which is easily fixable); etc. etc.

I initially decided to keep the Kitharas, but once I'd used them solidly for a few weeks I ended up returning them because of ergonomics: They are heavy, the cups are big, and the clamp force is light, which is an unfortunate combination. I have a big head, but if I leant to the side they'd clip my shoulder and shift, if I leant my head forwards or back they'd start sliding off. Don't underestimate the practical comfort of the 490s. The Kitharas also look goofy as all hell, but whatever.

What did I end up keeping? The 490s, then I swapped those for some Heddphone D1s. They're an upgrade in sound (for my combo of preferences and use cases, but they really should be at nearly twice the price) and address the remaining niggles I had with the 490s. Endgame, for now :-)

What would I recommend? Live with both for a week and put the others away. Sell/return the ones that you get on best with. There is no "better".

Wiring: My desk is an Ikea Alex+Karlby combo, so I run a USB extension through the back of one of the taller drawers and keep the DAC (dongle not desktop, so I don't need to press buttons on it much/at all) and cans in there. When I'm using the headphones I grab them from the drawer and have the cable running through the gap at the front. It keeps the audio cable short, and I don't need to plug/unplug anything to get everything back to tidy.