LAST EDITED ON Jun-30-19 AT 09:54 PM (EDT)
 
Welcome newfriend. You are right that the writing gets better over time, but thanks to the unique way the universe was written, quality can be... uneven... at times.
If you have the time to read everything, read Core 1-4 then the rest in chronological order.
I’m going to be controversial here and recommend this if you have a strong desire to read in chronological order and not read everything.
Core 1-4
The Vocaloid Variations
Rite of Passage
The Vocaloid Variations: The Mother of Invention
Transformers: Flesh and Steel
Operation Archangel
Aegis Florea, Part 1: Commander Moreau
Star-Crossed
Split Infinitive
Manhunt
New Beginnings
Days of Miracle and Wonder
TWILIGHT
The Legacy of Korra Until Book 7
Aegis Florea 2: Commander Moreau Reprise
Symphony of the Sword No. 1: Das Lied von der Erde
Symphony of the Sword No. 2: Blood and Roses
Symphony of the Sword No. 3: The Unfinished Symphony
Shepard's 11
Bacon Comics Titans Vol. 1 No. 1: "Convergence"
Vault: Eyrie Productions Destroys the Marvel Universe
Lost and Found, or, a Time Lord's Holiday
Bacon Comics Titans Vol. 1 No. 2: "Welcome Home"
Bacon Comics Lensmen Two-in-One 2003 Annual: "Excessive Force"
Symphony of the Sword No. 4: Say You Want a Revolution
Bacon Comics Project Phoenix
Bacon Comics Raven: Blood Ties
Lensmen: The Brave and the Bold Presents "New Tricks"
Avalon 17 Presents Our Witches at War
CSI: New Avalon
Bacon Comics Rogue Squadron: Colonial Forces Special Flight Test Division
The Order of the Rose: A Duelist Opera
Last Transport
Lensmen: The Brave and the Bold Presents "Night of the Kissogram!"
A Lensmen: The Brave and the Bold Special: Weapon of Choice
Transformers: Cybertron Reloaded
Warriors of the Outer Rim

So Kris Overstreet and Martin Rose haven’t written anything in years, so while I’m not going to say that their contributions don’t need to be read, I wouldn’t worry too much. Days of Miracle and Wonder will make less sense if you don’t read Marty’s stuff. Parts of Twilight will make even less sense, but that might just be a sacrifice to be made.

If you have minimal time but can listen to stuff, say at work, several stories have audiobook type recordings that Gryph has done, listen to those in chronological order.
If you want to get someone else hooked/ stay hooked, play them the Symphony of the Sword audiobooks.

Happy Reading