This question has, in fact, been asked a bunch of times and I've even answered it already, but I can't find my post. Instead, I'll give you a short version.
The best Dragon Quest games to start off with are DQ4, DQ5, DQ8, and DQ11. The best versions of DQ4 and DQ5 are the DS or Android / iOS ones. For DQ8, it's a choice between the PS2 original (nicer menus, orchestral soundtrack) or the 3DS version (portability, extra content). DQ11 is getting an extremely good rerelease for the Nintendo Switch sometime this fall, with orchestral music and extra story content, but if you wanna play it now then the PS4 and Stram versions are fine too.
Of those four games, I personally like 5 the best. If possible, I highly recommend you give it a try.
As for the other games, you mentioned that you were curious about the Game Boy Color versions of the first 3 games. They're fine, but the amount of the overworld you can see is smaller than other versions, and the battle menu has trouble fitting so much text on a tiny screen.
Either way, I personally don't think the original three games should be your first, they're best experienced after you're already familiar with the series through later entries. This is because the later ones do a good job of making you care about the characters and the overall story, whereas if you have trouble appreciating the world exploration gameplay of the originals, then you won't enjoy them as much. This, again, is why I recommend starting with Dragon Quest 5. The story and characters in that game are just magical.
Last rule of playing a DQ game is to stick with it. The early hours are always slow, but eventually you reach a point where things get really interesting and / or exciting. I hope this post helped!
Woo, brokenhearted squad!
