Similar to you, I've used hard mode and would revert to medium mode for tricky sites, which is fairly problem-free. In the end, it almost made sense to just use medium mode.
Yeah, AdGuard definitely slows down even though the slowness in most cases would be acceptable for most people. But switching from ADG Desktop to uBO, the speed difference is immediately noticeable.
I tried the route of using uBO in hard mode a few years ago and it was not bad. But the amount of things I had to whitelist was a lot. So in the end didn't make much difference. Also just remembered, for whatever reason, at that time some sites with a lot of javascripts were slightly slower to load only in Firefox with uBO hard mode compared easy mode. That was a very odd thing for me because I expected the opposite.
I could never get comfortable with NoScript's UI. I used uMatrix when it was still a thing and uBO hard mode after that.
Agreed about uBO Medium mode with some only allow TLD rules and blocking HTTPs Rules. The below are my default in uBO but it gets tedious when some streaming sites require xhr whitelisting to work but still block the streaming ads.
! Block beacons, obsolete plugins and websocket biderectional data connections on insecure websites
|HTTP://*$ping,object,websocket,important
! Block potentially unsafe third-party content linking to unsafe unencrypted websites
|HTTP://*$third-party,~document,~stylesheet,~image,~media,important
! Warn when opening webpages on top level domains and countries I never visit
||*$document,domain=~com|~info|~io|~eu|~net|~org|~uk|~ms|~gov
I use Edge for default browser because Microsoft Defender works best with it but I inevitably have to stream on Firefox for sites with Ads that I need uBO Origin for.
NoScript can be a little tedious and I miss that the Mcafee Site Advisor would tell you for example that it's just a site media server but uBO is my favourite for all around protection ugh MV3 /shrug though uBOL is fine in Optimal for ad blocking but I miss the control of Origin.
Sorry for wall of text. I tend to ramble on a bit when I'm reducing steroids...