It's been a while since I've read most of it, but when I was a kid the original run of Wally as the Flash from the end of Crisis up through "The Return of Barry Allen" in 1993 or whatever was my favorite run of the character.
"Return" is still my all-time favorite Flash story; there's just SO much going on and so many themes being explored in that one. Feeling pressure to live up to a legacy, being confronted with the idea that maybe your heroes weren't exactly the people you thought they were, feelings of inadequacy and failure when it seems as if you're not needed anymore, all that stuff. It's a really poignant arc. I love it to the point where I never really accepted the real Barry's return in 2009; to me, they'd already explored what might happen (even though it wasn't really Barry in 1993) and fully cemented that Wally was the "true" Flash, and had fully earned it by then. And, the 1993 story explored all of the storytelling possibilities of "What if Barry ever came back?" in far better fashion than what they did in 2009, so it all felt redundant.
This cover right here was one of the first Flash comics to ever jump off the racks and demand that I buy it. It was just so striking at the time.
I wasn't really following the storyline before that, but when I saw that cover I just had to know what was going on. From that point I was officially a "fan" of Flash; I'd like him before that and I owned a couple of issues but that's where I jumped on and stayed on, buying up the back issues and everything.
For all time, "The Return of Barry Allen" is probably gonna be the one story I pick to suggest to anyone as far as, if you only ever read ONE Flash storyline, that would be the one. There's other good ones but I'd always swear that's the BEST one.
To be completely honest, though, that arc was so good that most of the previous stories in the book up to that point weren't as memorable for me. Although issues #1 through 75 do tell a really great story altogether of Wally growing into his role as the Flash, some of the individual pieces are less memorable because the ending of that run is so powerful. I think the second-most memorable story, for me, was the one leading into #50, when he fought Vandal Savage and ended up getting the "liquid metal" costume to replace Barry's, which had been wrecked. That was always my favorite Flash costume; it was close enough to Barry's but just "modernized" enough to look contemporary and "cool".
Point of fact, this Annual was the first Flash comic I ever owned, and it's one of my favorite single-issues of Flash to this day. Also of note, my introduction to Guy Gardner, who I later became a huge fan of. But yeah, another book I love to this day:
I was like 5, so I wasn't really up on all the various goings-on in the wider DC Universe outside of Superman and Batman. I had no idea that the current Flash wasn't the first one, or all the stuff that had happened before, so this issue was an incredible primer for a first-time reader, basically telling you all you needed to know about the Flash legacy up to that point, going all the way back to Jay Garrick and the JSA. Which is ideally what books like this Annual are supposed to do, but some do it better than others.
So that was another huge one, for me. If the "Return of Barry Allen" story is the one Flash arc I'd recommend for anyone to read, Flash Annual #3 from 1987 would be the one single issue I'd recommend. I could literally read either of those any time, any day, and never, ever get sick of them. Genuinely some of the best comics ever made, easily.
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As for some of the odder elements of the early Wally run, it was sort of generally established at that time across the DCU that Wally was sort of an immature jerk who was dealing with serious "growing pains", both insofar as stepping into Barry's legacy and just plain growing up in general. He wasn't always portrayed in the best light, either in his own book or especially in Justice League Europe where he spent much of his time drooling over Power Girl in ways that would never see print nowadays. But it all sort of fit the trajectory of his character's arc. He made a ton of bad choices during that time, but it definitely made it all the more satisfying by the time he "cleaned his act up" and fully matured. It's the kind of thing you don't generally see in super-hero comics, where characters are either almost-perfect or chronic screw-ups with very little in-between. For most of the late-80s and early-90s, Wally was sort of right in the middle, always having good intentions (even if many of his actions were still rather self-serving) but somehow always becoming his own worst enemy.
If you go back and look, those early Flash stories were definitely some of the most enriched stories DC as putting out for its flagship characters at that point. Which is really saying something, as the DC run from 1986 though 1994 was arguably some of the all-time best material the company ever put out across the board. It was a true Golden Age for DC, and Flash was easily among the best stuff they were putting out, at a time when almost everything they put out was already great to begin with.