I use the Jabra Elite 7 Active, never had them drop out during a run. I'm guessing their other earphones would be just as good.

If you run outside check out shokz openrun. Works great w 945. I am never going back to buds :)

Not earbuds, so feel free to disregard, but Shokz have worked great for me and IMO also safer than buds since I can still hear traffic etc. I have to content with traffic, so I must hear cars.  These have been rock solid for 3 years of regular use.

Any/all headphones and speakers that I have connected to my watch have worked really well.  

My favorite are ones that have the light cable that goes behind neck connecting them and have a small module for controls on one side.  find it easiest to use during a run or while working out.  Also can easily tuck one bud into shirt to run with one in to hear the sounds of the beach or birds etc.  Currently use Soundpeats Q30 HD from amazon - just a basic generic version/brand that I have been using their stuff over the past 5+yrs from them.  replace when they get washed&dried on accident , stepped on, etc... LOL   
Love they have the little wing peice that fits into ear and holds them.  

I've had mixed results with different headsets. The aftershokz (just shokz these days) work fine. I have hyphen 2 fully wireless buds, these work fine as well. They do not have a passthrough option, so you won't be able to hear your outside environment very well.

I also have the sony linkbuds s. These do let you listen to outside sounds. But they have some connection hiccups here and there when used with the watch. Work fine with my phone.

Mobvoi ticpods, also seem to have hiccups in the connection.

I have some jaybirds (with the wire behind your head). I think it was the X3's. Those had connections hiccups as well.

I bought the same. Now 60min and 90min runs done without any problems. Jaybird Vista woud have disconnected dozens of times.

Thanks 

Great, nice to hear they are working fine for you!

My AirPods work the best. I also have a pair of sunglasses that pair with the watch too. 

I have had several earbuds but after my Jabra sport broke last year, I bought the JLab Epic Air Sport ANC Ear Buds on amazon and I couldn't be happier. The battery life is just out of this world, I must have charged the pod 4 or 5 times in a year and I use them 5 or 6 times per week. I know there are lots of good ones around but just my 5 cents in case it helps.