This might be a good option when it becomes available: https://www.pine64.org/pinetab/
Otherwise the Nexus 7 works quite well. If you need something that can be more of a desktop/laptop replacement, I've been really quite happy with my Dell 5175 running Pop!_OS, and it worked well on vanilla Ubuntu as well.
@ko I forgot to mention 2 things about the Asus:
1.) Couldn't get the cameras to work, and I never bothered to sort out why as I never had a need for them.
2.) Auto suspend seemed to cause problems with it waking back up so I just turned that off and set the power button to suspend/lock instead.
@ko The Nexus 7 works well with UT. If you want to run Linux on something larger/more powerful, I've been happy with Ububtu 19.10 and Pop! OS on my Dell 5175, and Ubuntu 19.10 worked on an Asus t100 I had as well. I think Manjaro worked as well but I didn't play with it very long.
@linuxadopter A quick search came up with this https://www.kimovil.com/en/frequency-checker/TR/oneplus-3t
Would a Oneplus 3t work for you? It's currently being ported to Ubuntu Touch, and you could run LineageOS on it until it's stable on UT....pretty decent specs and they can be found for a good price.
The GearBoy Color App is nice, actually goes well with the Nexus 7....come to think of it, I should see if my 8bitdo controller will work with it 
I believe Dalton was working on it some months back (he had it in one of the QA streams and indicated it was rather difficult to work with). Honestly, just based on the specs it's not much of an improvement over the Nexus 5. Personally, I'm looking at getting the OnePlus 3T- seems like decent specs, more recent, and there's active work being done on porting it to UT.
How's the progress on the HTC 10? Also, is there a way to track the progress off the newly ported devices (OnePlus 3/3T, Sony Xperia, LG V20, etc..)? Postmarket OS has a nice example of what I mean: https://wiki.postmarketos.org/wiki/Devices
@MarkG_108 I did see that, but it doesn't show much detail as to what's working and what's not (or which channel the features are working on). It also doesn't reflect all of the currently ported devices...
I was just thinking, why not put a chart on the main UBports device page listing which devices have been ported and which features are working/not working in each channel? I see there are pages for each individual device, but perhaps one chart listing all devices would make it easier for new potential users to see what functionality they can expect out of each device. This might also make it easier to keep up with the new devices that are in the process of being ported (LG V20, OnePlus 3/3T, Sony Xperia X aren't listed on the device page for example). Maybe update the chart once a month to reflect the progress that's been made?
Have you tried just running Ubuntu 19.10 with Gnome on it? That's what I've got running on the 2 in 1 Asus Transformer and it works quite well, apart from the camera/hdmi not working (which may be hardware issues since I didn't test them before I wiped out Widows on it). If it works, it should be pretty easy to switch to Unity8 once it's stable.
YES! I can now stream my local jazz station on my phone, thank you!
I'm running Ubuntu 19.10 on an Asus T100ha and it works suprisingly well for what I'm using it for (basic websurfing, quick notes using Standard Notes, etc...). The only things that aren't working are the camera and the micro HDMI port (the latter may be a hardware issue as the port looks like it might be damaged). Just using Gnome for the DE but I'd think that Unity8 would work too. Also I've got a Nexus 7 with UT that I've been happy with- comes in handy when I want to try something out without screwing up my daily driver Nexus 5 
I can't speak to the others you listed, but htop works fine on my Nexus 5.
@PhoenixLandPirat It's definitely more suited for desktop use with a keyboard where you can assign keys to control the playback. I was happy how well it worked through the terminal though Definitely less resource hungry than a dedicated app with GUI would be...
You know, if you switch to Tidal you can run it from the terminal
4 Standard Notes, use the UT Standard Notes App on my Nexus 5 and 7
@MarkG_108 You could always contact the author and see if they'll work on it for the N5. Also, you can turn the flashlight on via the Battery section in the top menu.
So, you can't be trusted to not download an app that you've been warned about? One of the things that appeals to me most about using a Linux system (phone or computer) is that it puts ownership back in the hands of the user- if you break your system YOU can fix it. And luckily there's also a great community that will help you if it does break