Really? What you considering uplifting trance from 91, 92 etc? Same for progressive trance, give some examples. Tech trance? Bit surprised to see you say this.
Due to linguistic barriers and the state of music distribution, trance was mostly limited to Germany pre-1996 (with a few tracks from random places like Sweden, UK, Australia, etc. here and there, and the wave of Italian tracks starting in 1995).
Most tracks from that era never saw the light of day in other countries, which may help explain why the general trance audience's knowledge about this era is very limited, including people I know who have worked in the industry for decades and even people like Armin van Buuren who explicitly said there wasn't really trance (aside from a few examples) before 1995-1996 (the commercialization of the genre and the strong push to different countries started in 1996, possibly driven by Robert Miles' Children that came out the prior year and had insane success).
Thus, it may not be surprising either why many sources point to later years when it comes to the birth of at least half of trance's subgenres (especially the ones that only really started getting produced in larger amounts in the late 2000s like progressive trance that you have mentioned).
I give you a few proper examples:
Depending on how broadly or narrowly you interpret Dream Trance and how much you want to stretch its definition, it either started in 1991 with the Subliminal Mix of Moby's Go, in 1992 with Confession's I Found Love (Club Mix) and DJ Hooligan's It's A Dream Song, or in 1993 with the Gianni Parrini Remix of Roland Brant's Nuclear Sun (both artists became the key members of the Italian Dream Progressive movement in 1995, along with artists such as Mauro Picotto and Robert Miles).
For ambient trance, you have to look no further than Sven Väth, who (after the founding of Harthouse) started to help to define various styles of trance in 1992. What is relevant here is his track Transpulsation (released under his Pulsation alias), but Sensorium by Zero Gravity is another worthwhile pick. On a sidenote, many tracks like these could also be retroactively labeled cosmic trance in my opinion (if we also accept vibe-based categorizations such as balaeric trance) due to their strong sense of spiraling, cosmic, spacey sound.
As for Hard Trance, my favourite record to point out is Final Fantasy's Sometimes I See Your Mind E.P. from 1993 which houses three amazing hard trance bangers (Control Your Fantasy, The Sky Is In Your Hands, Sometimes), but you can go back until 1992 to find Influid's Mastermind. And, Hard Trance could be further broken down into smaller categories if you really want to. There's 'rave' trance, like Andromeda's Trip To Space from 1993 and Spacewalker's Tenerife Dream from 1994. There are those I already mentioned which Ishkur likes to call german hard trance (basically hard trance, just clocking at higher BPMs than productions from let's say the early 2000s). Then there's hard trance from the 2000s, and you could also make a case for a type of trance (infused by happy hardcore) like Meteor Seven's Signs of Life from 1994, and can define acid trance (characterized by the cutting lines of TB303/808) by pointing to various tracks from the NIP Collective (Brainstorm from 1993) and Nostrum (Trance on Ecstasy from 1994).
For Tech Trance (so a form of trance more focused on small vibrations, techical proficiency, creative layering of sounds and development and less about drawn out, extensive melodies), there's Solitaire - Chasing Clouds (Cosmic Baby's Free Gliding Mix) and Instinctive Spirits - Omen 01, both from 1993. The first is a production by Cosmic Baby and Jens Wojnar (they also did a vinyl-only remix in 1994) and the second is produced by the guy who released Master DJ Rob - Energy Base in 1994. Northern Lights by Mr. Oz & Larry Lush, plus Grace's Skin on Skin (Orange Mix) - which is also known as Orange (Original Perfecto Mix) - from 1995 are also great picks, although I guess you could also label them as Progressive Trance, and maybe even the prior examples due to their heavy focus on subtle harmonic shifts and sustained development, but then again, I think there's a lot of overlap between those styles.
So yeah, for Progressive Trance, I would also possibly pick from the previous examples. Or I could potentially point to Eden Transmission's I'm So High (Ubud Mix) from 1991.
And, while Vocal Trance is not technically a genre, I think (I believe it only became its own thing when trance started to becoming nothing like trance to begin with), there are some early tunes that incorporate vocals in a stylish and complementary manner. Confession - I Found My Love (Club Mix) from 1992, Snap - Do You See The Light (Dance 2 Trance Remix) from 1993, or Lotus Eye - Enchanted (Komatex Remix) from 1994.
Of course, a whole lot depends on how one may interpret subgenres (and it becomes quite tricky especially when it comes to progressive trance as there are multiple interprations of the world itself). Though I think my approach and understanding, that essentially each substyle of trance tries to emphasize a singular, specific aspect of proper trance makes the most logical sense.
Or I'm just realistic enough to know the current limits of my knowledge and don't want to make a statement about things I don't know (enough) about. I currently covered pretty much everything until 1994 and part of 1995 as I checked around 35,000 tracks from those years. I can't say the same for the years after that, and based on my current understanding of uplifting trance, it's primarily a thing of the late 2000s. I'll potentially revise and update my views when I reach the later years of trance music and accumulate more knowledge.