I need some advice on what to research next because I can't make up my mind, either Cloak or Defense or Planet Buildings.

Vygoid Builder
Rank 332 (Almost 333)
Battles: 76079 (Grand Legend)
Combat Rep: Harmful

Play Style: Mostly NPC, Some Mission

Cap Energy: 2134 (With all relays + all Ion Pulse Balistae online)
Max Energy: 2654 (With all relays + all Ion Pulse Balistae offline)
Energy Recharge Rate: 55/hour

Hull: 7478
Shield: 1316
Decks: 1893/1893
Attack: 3544
Defense: 2134
Scan: 1182
Cloak: 565
Upkeep: 487.3M (With Builder Profession)

Productions: (Artifact is in need of work)
Mining: 3264
Artifact: 2445
Research (+20% Vygoid): 9608 [Caps in 6 hours, EVEN with 2 Research Data Archives]

Research:
Thetacron Radiation (1/3)
Supernova Generation (0/3)
Force Obviation Fields (1/3) [For Obviation Barriers]
Cloaking Fields (1/3)
Syncopated Phase Matter (1/3)
Exergonic Inversion (0/3)
Continuum Analysis (2/3)
Trans-Core Hubs (0/1)
Phase Transference (0/1) [Currently researching]

I know that my artifact production is lacking, need more planets though. Any advice?

Stop putting rank points into engineers!

Put them into Decks and TO.

#1 - Get more arti planets!!!! Buy, beg, invade, scan, scan, scan, purge, scan

stop what your researching now and do finsih star lifting or whatever its called ( the +12 planet buildings ) thats your power source do that and everything will go up some more. from there id say it depends on play style and if legion needs the legion tech researched.

yes scan/invade/beg for good art planets AND good mining planets, builder proff is a uselsess crutch, sooner you get yourself off of it the better.

I'm Vygoid and i'll admit that the research bonus is a huge crutch as well, but at least its usefull, to a point.