Which would be considered the most stable version in terms of no crippling bugs in both ZQuest and ZC? (Including betas and alphas.)
The Most Stable Version?
Well, alpha 288 hasen't been tested a lot yet, but it seems pretty stable. alpha 254 was really good though. That'd be my choice.
The bomb count bug in 288 is a real annoyance (if only Windows got 291!). 254 was indeed very awesome in terms of stability and is one of the best builds we've had.
There was, however, the (isolated?) incident of Beta Link losing ALL of his progress on "TLOZ: Island of Dreams" due to a corruption. BUT! AS long as you have "Auto-Backup" checked and DO NO SAVE the corrupted file, you're safe.
1.92 beta 183, if you can live without looking at the overworld map more than once at a time, and 1.92 beta 184, if you don't mind Gleeok necks jammed into the west wall.
If you can't find them online, I can help.
The most stable ZC is indeed ZC 1.92 b183.
But if you want to know what is the most stable 2.5 build, then IMO build 254 is quite awesome.
Build 254 has ganked two quest files in the last month that I know of. Wouldn't call it especially stable.