I love my Steam Deck, have the LCD version. The battery is shit, though I always have a battery pack with me. The Deck's LCD screen is also meh. It's better after the update, as you can control saturation/colours better, but it's still meh compared to what I normally use.
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@Madmick said, the ROG Ally Z1 extreme is more powerful, and it has the benefit of native windows 11 (and Gamepass) support and a beautiful screen. I keep hearing that windows will come to the Deck natively, but nothing so far.
I had been going back and forth on getting a Deck Oled, or the Z1 Extreme, but now I'm only debating getting the Deck Oled.
I tried the Z1 Extreme a few weeks ago and the buttons/triggers/sticks feel like a shitty knock off controller.
If you're mainly planning on using a portable to use on a monitor, go for the Z1 Extreme. See if you can get both in your hands, maybe the Ally won't feel as badly for you. The Steam Deck for me fits like a glove, and the buttons/sticks and triggers feel great. It also has superior emulation support (Emudeck) but I hear that's also coming to the Ally.
One huge plus for the Deck are the track pads. I don't like their feel that much, but you can easily navigate the OS with them like a mouse. I hear they are improved on the Oled models.