In fact, this "rabbit hole" has been extensively discussed. Search the archives.
I compared the Pro-ject CD Box RS2T transport to my Simaudio 260DT transport and in my system (Wells Majestic integrated /Silverline SR 17.5 monitors/Aqua La Voce 2 DAC) the Pro-ject offered noticeably more detail.
Only you can judge whether a separate transport is worth the investment and this can only be determined by you listening to transports in your system.
Besides the Pro-ject, other brands to look into are: Jay's, CEC, Cambridge and, as mentioned, Simaudio.
Good luck!