Well, I see guys always going into the LHS and buying really expensive glow plugs imported from overseas, when we have local brands that work just as good, and they get to save money too. but then I suppose if you are overseas then our local brands would be the foreign brands.

I quit buying one expensive imported brand that was sold here after buying 5 glow plugs and having each plug last one flight before going bad if that long. Everyone else at the flying field was having the same issue too with it. I have not trusted them since. The company ignored everyone and acted as though there was no problem with the plugs it was all out fault. A year or so later it finally came out that they had a bad batch of plugs made.

Now when I was pylon racing I used Rossi plugs a lot. The O'Donnell glow plugs worked good for me too. I remember using the Glo-Bee plugs years ago and having pretty good luck with them. I have a couple cards of O'Donnel plugs to use up but they seem to last a long time, so it'll take a while. I remember using O-Donnell glow plugs in RC cars a lot too. The O'Donnel plugs held up pretty good with the high RPMs and nitro we all ran in the cars. The glow plug Saito puts on their new engines when you buy it seems to last for ages without going bad, so using those glow plugs is a good bet, but the Fox Miracle plugs work good in the engines for me anyway.
I recently discovered that the Russian glow plugs from the old iron curtain days are amazingly good too, apparently they used more platinum in their coil elements at the time.
The McCoy plugs are pretty good too.

But when I need a new glow plug I invariably replace it with a Fox plug if it isn't oneof the other plugs I am still using up. No sense buying an expensive plug from Asia here in the USA.