I don't find myself listening to much '65-'67, and nothing after July '90 (Vince was a great player, but he just didn't work in the Dead, IMO). Other than that, it's all good (well, all eras are good; you may find an off night here & there).
As to '84, I seem to remember (I think) that Alpine Valley was pretty darn smokin' that year.
And Uptown Theater Decemember '79 was fun.
And July '90 at the World Music Theater - Brent's next-to-last show - was amazing.
And Alpine '82 (John Cippolina & Zakir Hussein sitting in).
And lately I've given several listens to Filmore East Feb '70 (with the legendary Garcia/Kreutzmann/Lesh/McKernan/Green/Kerwin/Lee/Trucks/Allman/Allman/Oakley jams) - and will be doing so again very soon, I assure you!
And everything I've heard from the '72 European tour cooks.
But I really did love Brent. After the '90 World show, the friend I went with & I spent the next 2 days talking about how much he added to the band. His death was real kick in the gut.
Peter