Not really debating you, but must say result is user-dependent. My failure rate for all vids that I download is very low. Last year or so... I think I've downloaded about ... let's say 70 vids per 12 months (just over 1 vid per wk) so that already tells you I'm a bit picky and maybe that biased my results... ANYWAY, out of 70 vids, I think I have playback failure for 1 or 2 vids (or ZERO vids!)
So I am really confused why you guys have such high failure rate with any group, particularly thz.la
My own experience with the same groups, is exactly reverse from your experience.
Thz.la: excellent (but definitely not perfect) video quality, semi-transparent, non-distracting watermark, but unfortunately the watermark area is larger. Fairly reliable release schedule, for the kind of vids that I like. In a good year, I download only 2 non-Thz.la vids per 70 vids. No ad, no trailers. Sadly their releases for the past month is way way behind schedule, so I've to re-start checking out other release groups. I won't know what to do if thz.la dies or don't recover from the current slump. Must also admit that their playback failure rate is greater than zero. But it is low enough that I can overlook it.
White text: excellent quality, tolerable watermark. Very unreliable release schedule, before I full became Thz.la fanboy, I was especially hunting for white text releases, but more often than not, can't find my wanted vid. About 2 or 3 out of 10 release has audio sync problem. I have 3 possible solution: mute button, manual adjust delay of the audio track in the player (Kodi or VLC) control panel, re-encode the vid myself with corrected delay (usually in 1000-1600 ms range) . Most of the time I just mute it.
Unknown group or groups: "perfect" (?) quality, NO watermark. Problem is they are even more rare than White text. Purely luck (for me). Perhaps might find 3 vids a year? Often comes in inconvenient container (WMV, MKV) and huge file inefficient compression.
Yellow text: super fast, super easy to find releases. Their release covers at least 98% of my want list. But I can't stand their older yellow watermark. I hate their SD so much that I often give up on a vid if yellow text is the only group releasing it. Now they are doing 1080p release with a more tolerable white watermark, I consider them an acceptable last resort. Also their release starts with 1-2 minutes of super annoying ads for casino and online sex. Takes me 5-10 minutes to trim those (doesn't save any disk space, but super annoying everytime I play the file). 5 mins isn't much, but I don't enjoy wasting 5 mins on such chore if it's 50+ vids per year. Before thzla went to a slump, I was so happy with my life since I don't ever need to download yellow text vids.
About compression ratio: I am no expert, I just use thz.la as gold standard: about 4000 kbps, about 4GB / 120mins vid for 1920x1080p. Often you come across huge files 6000+ kbps (6GB for 120 mins) that may stutter more than thzla. Or once in a while you still see DVD ISO being uploaded, for that you get about the same file size about 3+ GB / 120 mins but only SD quality, 480i instead of 1080p. And uncensored vids (Caribbean etc) may be 3.5 to 4.0 GB for 60 mins 1080p, these fails to playback on Atom processor, but fine on i3 and up. For those I sometimes take the trouble to re-encode the vid to 720p or 1080p for playback in my bedroom. That usually take 20-30 mins on my i7, not a fun chore, but I only do a few such vids a year.