With my first ever full run of Wiz1 successful, I moved on to Wiz6 as some of you know. Now I've put in a few hours and I've just jumped a deep chasm with rope and hook.
So far - and I accept that this is oh so preliminary - Wiz6 seems like the bigger game, Wiz1 feels like the better game.
Most additions jumping from Wiz1 to 6 are positive ones; more spells, more classes, more options, more detail, etc. But Wiz1 has a clean and pure intensity in how it plays. You're on level 3, you want to get to level 4, and there are a clear and finite set of resources and dangers to think about. You get in the zone. Similarly, I enjoyed UU1's level system far more than UU2. Playing Wiz6, I find myself backtracking a lot more across different areas, trying different keys on each door, fighting a lot more random encounters, getting more bogged down - even though I found it really interesting to, say, hear more about the royal family's rooms and the fate of the skeletons on the floor. (It's really long-winded though. Hilariously, if we copied and pasted the same lines onto POE everybody would be talking about the verbose narration. I do think it's more appropriate here, at least.)
The weirdest point for me is how I played Grimoire before playing Wiz6. Now I see how Grimoire is an extremely close copy/homage/variant in many ways, right down to things like the design of the alcoves in the walls. So it's a weird position where it feels like if I want a 'big' Wizardry, then Grimoire is the superior version. Time will tell as I keep playing 6. (Who knows, maybe I'll also revisit 8 after my 5 hour stint 20 years ago.)
BTW running I suppose a pretty humdrum party of Samurai, Valkyrie, Ninja, Bard, Priest, Mage. The Samurai and Valk started as Priest and Mage for just one level, though I'm not sure if it was really worth it. The Priest is now approaching level 7ish and I would make her a Valk too, but there seems to be so many useful higher level spells to earn. As with Grimoire, it feels like bard sleep is your Awesome Button for the first few hours.