Hello! My bottle of Private Collection Tuberose Gardenia is several years old, and I haven't smelled a recent version so I am not sure if they've changed the formula a bit. I hope they haven't altered it. Sometimes a fresh bottle of perfume needs a few months to sit for a bit and settle down, so I would set it aside and try it again in a few months, but it definitely should not smell harsh or synthetic at any point.
I recall that Dame Perfumery used to sell samples. I don't know if they still do it, but I would recommend buying some samples to test their gardenia perfume, while waiting for them to re-stock. It's a good sign that it's sold out. Perhaps they had a Black Friday sale recently. Samples are great because you can try them at home over a period of several days, which helps you to truly evaluate a fragrance, and decide if it's for you.
Thank you for the kind words.

My nose is not the best, especially in winter when the cold air and heating seem to combine to blunt my sense of smell a little. I fare better in the warmer months when I can smell everything clearly. Regarding Chanel Gardenia, I only have the older versions in EDT and pure parfum. Chanel changed their exclusifs collection from EDT to EDP a few years ago. I have not tried their EDP (the current version) of Gardenia, but I would assume that they have not changed it drastically so it should still be somewhat close to the older versions.
Regarding comparing the three perfumes, I will post my preliminary thoughts now, based on my recollection, but since it has been a while since I wore them, I will also test them out during this week and post an update soon. I need to find my Soliflore Gardenia sample, which is somewhere in my sample box.
Gardenia and Tuberose are often used together in perfumes, but I find them to have different personalities. Tuberose is a distinctive white floral, sultry, a little bit carnal, rich, and really quite stunning. I have a handful of tuberose perfumes that I love, including Malle's Carnal Flower. Gardenia is softer than tuberose to my nose, creamy, lush and beautiful.
Of the three perfumes, I find Lauder's Tuberose Gardenia to have a higher presence of tuberose in it. I would say (based on recollection) that it has a fairly equal blend of both tuberose and gardenia and is a well-constructed beautiful floral fragrance. Soliflore Gardenia is more of a true gardenia with the creamy, nutty (for want of a better descriptive word) scent of gardenia flowers. Chanel Gardenia is really Chanel's interpretation of gardenia, an elegant, floral scent that is delicate, but at the same time quite complex. Tuberose does not play a prominent role in Chanel Gardenia (as it does in Lauder's gardenia). In fact, my nose does not pick up any tuberose in Chanel Gardenia.
@880 has given a good description of Chanel Gardenia upthread. The vanilla in Chanel Gardenia is really not at all prominent to my nose. In the hands of master perfumers, notes like vanilla are handled with expertise, which results in imparting a delicate warmth and subtle nuances rather than an outright foody note -- at least I find that to be the case in Chanel Gardenia. My apologies for describing and comparing these perfumes based on memory (which can be faulty) rather than actually trying them on. I will do so in the next day or two and update.
Thank you for the Neutrogena oil recommendation. I've been loving body oils lately, so I will definitely be ordering it and am looking forward to trying it.