I've got a number of favorites from this era. I'll go in chronological order....
Survivor Series 1990
This was the first ppv event I ever watched. I didn't watch it live, but after I started watching wrestling on TV shortly after Wrestlemania VII, this was the first ppv event I rented from the video store, and I watched it religiously. I loved the Survivor Series elimination matches, and I still wish WWE went back to this formula for having an all elimination match ppv event like they did for the first 5 or so Survivor Series events. I was really hoping they were gonna go that route this year (which I will be attending in Indy!), but alas it wasn't meant to be. This ppv is most famous for being the Undertaker's debut, which of course became one of the most important moments in WWE history, though no one at the time knew they were witnessing a monumental moment. But each elimination match made complete sense. The teams were put well together. Every major feud in the company at the time was highlighted in the elimination matches. And for the first and only time in Survivor Series history, they had a final elimination match between all of the winners in the previous matches to determine the ultimate survivors. I still feel that this is the best Survivor Series ppv of the original "true" Survivor Series events. It was never the same after this one.
Summerslam 1991
This is the most underrated Summerslam ppv event ever. I'll admit I'm biased because this was the first ppv event I ever watched as it happened, but it was still a really fantastic show from top to bottom. All of the feuds that were taking place that summer culminated at the event. From the LOD finally defeating the Nasty Boys for the tag team title (in one of the WWF's first No DQ, No countout matches), to Virgil finally one-upping the Million Dollar Man, to Bret Hart's rise up the singles ranks by winning the I-C title in the best WWF match of that year, to the mystery of would Sid Justice play fair and not be swayed to the dark side of Sgt. Slaughter and company, to the Big Boss Man defeating the Mountie and forcing him to spend the night in jail (which are still some of the most entertaining segments ever put on by WWE), and of course the wedding of Miss Elizabeth and Macho Man (which had been years in the making for WWE fans), it was just a well booked, highly entertaining show. Even the matches that were just thrown together were good (IRS/Greg Valentine, the opening 6 man tag, etc.). The only disappointment of the event was the lack of Undertaker and Jake Roberts, but it turned out okay in the end. Great event.
Royal Rumble 1992
This is a ppv event that's here solely for one match, but it's one of the greatest matches in WWE history (yeah, I said it), that of course being the main event, the Royal Rumble. Although the ppv also featured the only title win in Roddy Piper's WWE career, which was a great moment in itself. But the Royal Rumble match itself, from the booking, to the participants, to the commentary, to what was on the line for the match (winning the WWF championship), it was just overall one of the finest presentations the WWE has ever put on. A classic that never gets old.
Wrestlemania VIII
I'm not gonna lie, I'm biased because I attended this event (my first ppv event I attended, my second overall live event of any kind I attended), but this was one of the best Wrestlemania events in the early years of Wrestlemania. It had the third highest attendance of any event until the stadium shows of the 2000's and beyond. We had two all-time classic matches with Bret Hart/Roddy Piper, and Macho Man/Ric Flair. We saw the rise of two future icons, HBK and Taker, and we saw Hulk Hogan's swan song in the company for awhile (also Sid's and Jake Roberts, and really Roddy Piper's). And the commentary (which I would discover later on after getting the video of the event) was some of the most entertaining ever. Heenan and Monsoon were on fire for this event. A great, highly entertaining Wrestlemania all-around. The third best Wrestlemania of the 1990's, only behind X (1994), and XIV (1998).
Summerslam 1992
The atmosphere here was incredible. We got a top 5 match in the company's history in Bret Hart/British Bulldog. We got a highly underrated classic with the rematch of Macho Man/Ultimate Warrior. And the rest of the card provided solid matches and moments. From Rick Martel and HBK's underrated match, to the opening tag team match with LOD and Money Inc., to Taker's awesome entrance against Kamala. Even Nailz/Virgil and Repo Man/Crush were interesting filler matches. The crowd and the atmosphere though was what made this event one of the best in the company's history. It also could be the biggest legitimate crowd WWE has ever drawn at a ppv (right there with Wrestlemania 23).
Wrestlemania X
One of the best Wrestlemanias of all-time largely due to two matches. Bret/Owen, and HBK/Razor. Though Macho Man/Crush (in Savage's final Wrestlemania match) was highly underrated, and pretty groundbreaking for the time. Plus Bret finally, truly ascending to the top of the company was a great moment. The celebrities on hand were actually entertaining. And having a Wrestlemania in Madison Square Garden always adds an extra feel to the event. Great show. The only thing that hurt was the lack of the Undertaker though.
I'd say those are my 6 favorite events of that time period.