Don't think Gamepass is half as good as people make it seem. For one, it's basically a glorified rental service, with games cycling out over time and you not really owning anything. Sure in theory once a game cycles out you can buy it at a discount, but I actually prefer the Sony Alternative where the free games they give you are forever yours to keep as long as you have an active subscription to access them. I currently have 235 PS+ free games acquired over the years, and I consider those part of my permanent game collection. Add the new PS Collection and PS Now to that and you have a pretty decent service as it is, and one that will probably get even better next gen due to the MS competition.
As for Gamepass, yes it's a good value if you enjoy first party ms titles and a couple exclusive zenimax games, but those are few and far in between, and you're paying each month, even though there's probably only be a couple games each year you'll be really interested with. For now, when I look at the library , there's not that much stufff I would want to play / that I don't already own, which explains why i'm lukewarm about the prospect. Then again I'm pretty indifferent about my 235+ PS+ games too... So I guess it's the same...
In the end, I think the big difference is Sony will give some / many their games for free to keep forever after a couple of months, versus Microsoft which will rent their games for free at the start, then eventually cycle them out of the program later down the road. Then again with the current conversion from live to gamepass deal going on it's a pretty good deal, I just find it hard to justify buying 180$ worth of live so I can get like a couple MS exclusives and maybe elder scrolls 6 in the next three years.