Give me your best powder for each.

red dot or promo for 12 ga win wst 20 ga unique or universal clays is also good 20 ga

I like Clays for 12 and Universal for 20

Clays for 12 ga. International for 20 ga. 3/4oz. Universal for 20 ga 7/8oz loads.

Target or hunting loads?

I only reload for 12 gauge so I will be the basis for my reply.

Your question would be like a mechanic stating that any one particular wrench or socket is the best. For example it would be very difficult justifying the use of a 1\2 inch socket on a nut or bolt that was a 7/8 inch size.

Gun powder is the same idea. Powders are manufactured for specific ranges of velocity and shot charges. For example Alliant's Extra Light is a very good choice for 3\4 or 7/8 ounce 12 gauge loads it would be a very poor choice for 12 gauge 1 1\4 ounce loads.

Therefore before anyone can give you advise on "the best" I would think they would need to know what type of loads are you planning on reloading.

So in 12 gauge shells what do you want to reload? Low Recoil? Really fast shells? Heavy magnum shells? Etc?

Both 12 and 20 would be for bird hunting. Dove, quail, woodcock and grouse. The 12 ga would be 1 oz or 1 1/8 oz the 20ga will be 7/8 or 1 oz. Both will be 7 1/2 or 8 shot maybe some 9 shot also.

The powders I listed are the ones I use for the same type use plus trap and skeet. There are of course other powders that work and for years I used Red Dot for the 12ga and switched to Clays shortly after it came out. Good success with Clays led ne to Universal for the 20ga.

It depends on which hull I load. I either load Win AA’s or Remington STS. Both are tapered hulls.
The Win AA has less internal volume. A dense powder with less volume helps with stack height to get good crimps.
12-Tite wad works well in Win AA hulls.
700x in Remington hulls

20-I like WSF in Win hulls
Universal in Remington hulls

For magnum field loads in 12 or 20 I like Longshot.

Shot shells are a lot simpler to load than metallic cartridges. In today’s times, I use what I can get my hands on....

For 1 ounce and 1 1/8 ounce target shells I like Red Dot and Clays. You will have to use an appropriate wad depending upon your hull to achieve the correct stack height for good crimps.

Smokey Bear made a good point about the availability of supplies. Right now reloaders are loading what we can get. A few months ago I was able to purchase NF Nitro 100 powder. I have never reloaded this powder before. The Australian Defense Industries has published a chart that groups similar powders. Here is a link to the chart.

http://www.adi-powders.com.au/powder-equivalents/

Using the chart I see that Red Dot, Clays, and Nitro 100 are listed as equivalent powders. Equivalent does not mean identical. Just similar. Since I like Red Dot and Clays I expect that I will like NF Nitro 100 as well.

Accurate Arms, Western Powders, Alliant Powder, and Hodgkin all have online load data available. Always use a scale to check the amount of powder thrown by your powder bushing. Never blindly trust the bushing tables.

I agree. I use to load red dot in 12 ga. 40 years ago. Just looking to see if something better has come along after that many years. I never reloaded 20 ga. I have 8 pounds of H335 I’m working on trading for 12 and 20 ga. Powders. Thanks for everyone’s input.