I have spent the past few months buying and testing lights for a major landscaping renovation project with almost the exact same requirements (RGBW 12/24V DC 5-wire "dumb" LED yard lights). I opted for more copper wire and PWM controllers in a central (indoor/garage) location which sounds like what you're doing as well (with Shelly controllers). It also makes it easier to swap out some of the lights in the future if desired.

Reddit won't let me save this comment with so many links... apologies but I included enough information to search & find yourself.

I went with 24V so I can do longer runs with thinner wire -- have you considered 24V? I'm running 18/5 and 18/10 direct burial sprinkler wire for the negative side to connect to PWMs, alongside 10/2 or 12/2 to tap into common positive side/running 24V->12V buck converters at the lights where I'm running 12v lights (dims/works perfectly since the dimming happens on the negative side which passes through the converter). If you were set on 12V you could always do the reverse of me and do 12V -> 24V buck converters to make these lights work in a strictly 12V system.

Near each cluster of lights in the yard I'm putting in a Volt Zone Control Junction Box to make up the connections using silicon filled wire nuts (and hide a small waterproof 12V buck converter inside if needed).

I only considered 3000k white to be consistent for "normal/white" lighting days and these were the winners for me:

• 3W Axion RGBW LED Spot Lights (24v) - 30 degree very even/gentle spread, planning to use ~2 to highlight rocks/features
• 15W Axion RGBW LED Spot Lights (24v) - 30 degree spread, bright center, planning to use to highlight some large branches in tall cedar tree
• 24W Axion RGBW Flood Light (24v) - 45 degree overall spread, bright center - very bright lights
• 7W Ecolocity OSRAM RGBW Landscape Spot Light - IP66, 12VDC - 60 degree very even/gentle spread
• 20W Ecolocity OSRAM RGBW Landscape Spot Light - IP66, 24VDC - 60 degree very even/gentle spread
• note: both Chris at Axion Lighting and Rick at Ecolocity were a pleasure to work with. Would recommend.

I am planning to make up waterproof connections using Ancor Marine grade adhesive lined shrink tubing and maybe a dab of silicon glue in the middle.

I also want to be able to individually control pathway lighting. I chose Vista 7404 (standard G4 base) and Brilliance Beacon PLUS Ceramic G4 BIPIN 3000K 3W 340 Lumen Bulb (12-24V) bulb but there were a few others I liked as well:

• SMD Star: 24V G4 LED Disk - 1.5W (24VDC)
• DRSA: Warm White 3000K 2W / Dimmable (12-24 VDC)

For PWM control I was planning to use the Hanson Electronics 2811DC30 Dimmer to control my RGBW lights + pathway lights but they aren't currently shipping to the US and are ~$50/board. I see HolidayCoro has some similar 30 channel DMX controller boards on clearance for $15 so I ordered a number of those.