The best place to start for Half-Life 2 Beta?

[IvanTheSpaceBiker]

  There are lots of maps and mods packs for the HL2B that are kinda overwhelming, does anyone know where to start looking from experience?

[Витой]

Well, I guess you could start by checking the original 2003 leaked build just to have an idea what it was. But it's not really necessary.
To more or less comfortly play the HL2 beta you can download Mega Build and start with September 2003 Storyline mappack. These are maps from the original 2003 build but fixed.

Then you could check development eras mappacks fixed by me and Toast the Fox. You can check 'Maps List.txt' file, located in the main folder of each mappack for full maps list.

Also there's E3 mappacks: E3 2002 (one and two) and E3 2003

And finally there's bunch of HL2 beta mods and map fixes that could be found at downloads section and our forum.