Oh you've really opened up a can of worms here. Everybody's got a fave, and most of us have very compelling reasons why they like them.
Since I learned from a pro, I got to try several different brands before I bought any of my own. The first ones I bought myself were Clover bamboo circulars, which I like but in the larger sizes (US 10 or larger) the cables tend to be a little stiff and if they're stored for any length of time at all, it takes them a while (or a bath in hot water) to unkink. But all of my DPNs are made by them, except for one set of Crystal Palace US 8s that I didn't buy for myself.
I've used Addi circulars, and they're nice enough (the stainless steel ones at least). I like the long "back" where the join is for Magic Loop because it makes it easier to get the needle into the stitches backwards when you're changing sides. But they tend to be rather dear in the pricing department. I've also heard from the folks at the yarn store that some of them (I'm not sure which ones) "turn green", which I'm guessing is caused by oxidation of the nickel plating. Can't confirm or deny this since I've only used the stainless and didn't have any such problem myself. Also, I've heard people who use their interchangeable sets complain that the tips can unscrew without warning. Again, can't confirm or deny, just repeating what other people have said.
My "go to needles" though are Hiya Hiya stainless steel circs. The cables are limber (up to a US 11 anyway... I don't have any bigger than that) the joins are smooth, there's no plating or anodizing to wear off, they're durable and despite being steel, very lightweight. Plus you can get them in a HUGE selection of sizes and lengths from US 00000000 to US 15 in lengths from 9" to 60" And they cost less than the Addis too. I haven't tried their interchangeables but reviews suggest that they're equal to or better than most.
My girlfriend is a huge fan of Knitters Pride Dreamz (I think that's the name). She got their interchangeable sets (both the base and the "bulky") and swears by them. I have some 10.5s made by them that I just got and have no complaint with them (except that the 10.5s have a dark finish and I'm working in a dark, multi-tonal yarn). They're also color coded by size, and made of hardwood (rosewood?) so they're smoother than bamboo and less prone to get scratched up or gouged.
I've also got an ancient interchangeable set (antique actually) made by Boye that is... well, there's one cable in the set that I can actually use, the rest of them make great stitch holders. I use the tips for binding off sometimes, but for the most part they're just collectibles that somebody gave me.
I've used plastic needles, but in general I don't like them much and I couldn't tell you who made them anyway. But in smaller sizes -- especially with straight needles -- they flex too much for my liking. Larger sizes don't have this problem -- usually.
But as for the "best" needles? You'll get as many answers to that question as there are replies to this post.