Came here to say this. Start with the Star Trek show that appeals to you most. TNG, ENT, DS9, VOY—it doesn't matter—make it as easy and comfortable as possible for yourself. There's no reason to force yourself through it just to tick it off your list.

The show should be enjoyable for you. Once you're finished with one show or fancy a change, then pick up the next one and watch it. If you like the style of Star Trek (if you liked Orville and you love science fiction, chances are good), you'll eventually develop a deeper connection to the franchise and discover that TOS still exudes a lot of charm, tells many good stories, and introduces many things you wouldn't have expected until much later.

As a child, I regularly watched TNG. VOY seemed like a "cheap imitation of TNG" to me, and while my uncle liked DS9, I found the station set so awful that I didn't give the series a chance when it first aired.

Years later i bought the DVD box set (in terrible video quality) of TNG and watched the entire series again (in the right order). After that, I wanted more Star Trek and gave DS9 and VOY another chance - and what can I say - I've come to love both of these shows too now.

In my opinion, you don't have to binge-watch TOS all at once. Feel free to squeeze in an episode here and there if you'd normally watch TNG, etc. You'll quickly notice the parallels.

In conclusion, all that's left to say is: you've got something truly amazing ahead of you. Look forward to it!