Note: This list was already existent, I just updated it and moved some brands around. If anything looks weird or out of place i may have overlooked it.
We've broken this section into 4 categories:
1: Bad
2: Questionable
3: Good
4: Highest quality
Bad
Absolute
American HiFi (Rockwood)
American Pro
Audiovox
Automobile
Becker
Blackmore
Boschmann
Boss
Craig
DHD
Dual
Emerson
JDL
Jensen
Kenford
Kole
Kraco
Kronik
LA Sound
Legacy
MA Audio
Optimus (Radio Shack)
Pheonix Digital
Planet Audio (Boss, by any other name)
Power Acoustik
Profile
Pyle
Pyramid
Rockwood
Sound Storm
Sparkomatic
SPL Audio
Stetsom
Thump
Ultimate Sounds
Urban Audio
US Amps- the newer stuff
Visonik
Volfenhag
Questionable
Alphasonik
Autotek
Audiobahn
Audiopipe
Blaupunkt
Aiwa
Crunch
Elemental Designs (eD)
Hifonics
Hollywood
Kenwood (amplifiers)
Lanzar
Lightning Audio
Matsui
MB Quart
Nakamichi (newer products)
NVX Audio
Onyx Mobile Audio
Panasonic
Phoenix Gold (ask on specific models)
Pioneer (amplifiers and speakers)
Precision Power (PPI) (newer non-US made amplifiers)
RE Audio- newer stuff
Rockford Fosgate (lower series products)
SAS Bazooka (all products)
Sony Xplod
Vibe
Good
Alpine (amplifiers, Type-R speakers and subs)
Altec Lansing
Alumapro
Ample Audio
Ascendant
Audio Development
Avionixx
Boston Acoustics
Cadence
Cerwin Vega (subs)
Clarion (head units)
Clifford (alarms)
Cliff designs
Coustic
Crescendo Audio
Crossfire
Crystal
DC Audio
Directed (DEI)
Dynamat
Earthquake
Eaton
Helix
Hushmat
Illusion
Incriminater Audio
Infinity
JBL (amplifiers)
JVC Digifine
Kenwood Excelon (HU)
Kicker
Kinetik (batteries)
Lunar
Massive Audio
Memphis Audio
MTX (amplifiers)
Orion (newer products)
Phoenix Gold (some models)
Pioneer- HU's
Polk Audio
Powerbass
Rockford Fosgate (Power Series amp and subs)
Second Skin (deadner)
Skar Audio (owner/company seems to be very shadey/unethical)
Soundstream
SSA Audio
Stereo Integrity
USAcoustics
Viper/DEI (alarms)
Highest Quality
a/d/s
Adire
Alpine (head units, signal processors)
Arc Audio
Audax
Audio Control
Audison
Brax
Butler Audio
CD Technologies (CDT)
Diamond Audio (HEX)
Digital Designs (DD)
DLS
DynAudio
Eclipse (Fujitsu Ten)
Esoteric Audio
FI Audio
Focal
Gladen
Harrison Labs
Helix
Hertz
Hybrid Audio
Image Dynamics (ID)
JL Audio (W6v2, W6v3, W7. ZR components,Slash and HD series amps)
KEF Kar components
Kove
Luxman
McIntosh Laboratories
MMATS
Morel
Mosconi
Nakamichi (Older products)
Ohio Alternator
Orion (older products)
OZ Audio
Pioneer Premiere (head units)
Precision Power (PPI) (Art series amps, old)
Rainbow
Resonant Engineering (RE) Older Stuff
Rockford Fosgate (older 1980s and 1990s models)
Sinfoni
Streetwirez
Stinger
Sundown Audio
Treo
Tru tech
US Amps (older amps)
Wrangler Alternators
XS Power (batteries)
Xtant
Zapco
Zed Audio
*Funky PuP
I hope this helped good luck mate!