There are BN’ers here who have a lot more experience with this house than me, but I would say Angel is a good place to start if you want to explore this house. I would caution against blind buying it as I think it is kind of a love-it-or-hate-it kind of fragrance. Mugler is a house that does not release new pillar fragrances often - for women’s releases, I think there have only been three since Angel was released in 1992 - Alien, Womanity, and Aura. It wouldn’t be difficult to sample all 4 of these. The rest of their releases are flankers (different variations of these pillar fragrances). If you’re looking for a feminine fragrance, Angel Muse EDP is really good, quite popular, easier to wear, yet smells similar enough to the original Angel that you can recognize it as a flanker, if you’ve smelled the original. I would almost suggest this one over the original Angel, but I also was not a fan of the original.
My personal favorite from this house is Aura, which was released just a few years ago. I think it’s Mugler’s best pillar release since Angel and a modern masterpiece.
Do not blind buy Mugler fragrances. They can be pretty controversial. They are love or hate it sort of scents.
I think the first ones you'd want to try are the pillar fragrances, which like Wingie mentioned are released few and far between (at least in their mainstream releases). So A*Men and Alien Man for masculine, Mugler Cologne for unisex, and Angel, Innocent, Alien, Womanity and Aura for feminine. This will give you a good view of the house. After that, you can go down the flanker rabbit hole, because there's a shedload of those.
I personally like their flankers. There was an Angel leather edition a few years back that was amazing, their 'Pure' A*Men flankers are good, and their yearly summer flankers for Angel and Alien tend to be fun.
Thank you for your feedback Wingie. I am beginning to understand why everyone mentions that it might be love-it or hate-it kind of fragrance. After reading and listening to some of the rave reviews I had considered the option for blind buying it but as you and others have suggested it might be wise to try it out first so I will first sample the scents and proceed further with it.