I have a few different types I use but for the most part I love Robison Anton. My favorite for the neon colors is Madeira Threads though.
In one of the yahoo groups I belong to one member said she swears by Kingstar for their metallics and other types of thread from Kingstar. The one who mentioned it said she never has to do anything to help her machine stitch with that brand. The owner of the group tried it because her machine did not like metallic and she's been singing the praises of that thread ever since. You can find that here
If you have problems running metallic thread in your machine, you may want to try that brand to see how it runs on your machine. Their customer service is great and they were nice enough to send me a spool to try at no charge.
Sadly, I have to say that my opinion differs greatly from all those who have tried it from that same group. I am VERY happy I did not buy a lot of that thread because I do NOT like it at all. My machine rarely has problems with metallic thread, but that was cheaper and it's hard to locate Madeira near here any longer so I wanted to find a new brand. This one kept breaking in my machine no matter which way I had the spool and if it was covered by a thread net or not, horizontal or vertical. Nothing I tried worked with my machine. I had problems with that thread flying off the spool extremely fast, unwinding nicely but not when I wanted it to be coming off. LOL All the members who also tried it loved the Kingstar brand so I'm not sure if those who did try and had the same opinion as myself haven't posted or if I'm alone in my assessment of it. I will say however that there were enough that liked it that you should not rule that brand out just by my testing of it though since that would be unfair. Their prices are good but to be sure, I'd only buy one or two to see if it works well in your machine.
I know many of our machines can be tempermental with threads so my thoughts would be to only buy a couple colors of any
new brand you want to try. You certainly don't want to spend $50 or more only to find your machine doesn't like stitching with that. It's no fun when you are using your machine if you have to babysit the thread to prevent breakage and problems.
I may have to try Marathon to see how that runs in my machine. I do love Robison Anton and I have stuck with that because it runs beautifully in my machine and I love the colors. I also try to buy that since it's from my dealer and every dollar I can spend there helps her sales which will hopefully keep my local dealer from having Viking shut her down for lack of sales. Of course, me saving money on what can be a very expensive hobby is important too.