Re: They're fast when you want to do stuff...
There are two obstacles that I would need to overcome for me to move from Adobe - I'm on the £9.95 per month photography plan, doing all of my work on a 12.9" IPP.
First is I would need something that works as well as Lightroom when it comes to image management. I've looked at some of the possible alternatives for my use-case and they're all somewhat lacking - ON1 in particular came close but image editing wasn't stellar on the iPad which brings me to point second.
Second, I would need to re-learn all of the editing techniques that are so familiar to me from ACR and LR, things that I do without needing to really focus on until it comes to refinement. None of the alternatives, including Affinity Photo, work the same way as does LR which makes for me, any level of editing both painfully slow and hit or miss.
One additional point, the current version of LR CC on iOS has just gained some powerful mask selection capabilities as part of the rolling upgrades the cloud versions get. If I'd been on the perpetual licence I'd likely have had to buy a new version of LR to get it - Adobe being Adobe. That and the fact my plan includes 1TB of storage makes it far better value to me than any of the alternatives. As ever, YMMV.