The Bare Essentials of Knitting Needles

I've finally finished going through the knitting curriculum with my mom-and-daughter student team, and it's time to get started on the "final project" (aka their first real pattern). For now, I'm lending them my needles since I don't want them to spend too much money until they're sure this is a hobby they want to pursue in the long term. I've only been knitting for 4 years, but in that time, I've made a wide of projects – everything from hats to lace shawls to amigurumi toys. Very quickly, I realized that each pattern seems to demand a different size, length, and type of needle, so you could easily spend a lot of money buying every combination known to man. For a minimalist like me, here's what I consider as the most basic sets to own that will cover most every project:

1) Interchangeable Circular Needles
Circular needles are basically two needles joined by a thin cable. They are commonly used to knit items in a circle, such as a sweater or hat.

Knitting in the round on circular needles (source: WonderHowTo)

Circular needles can also be used as straight needles (aka "regular" knitting needles) for flat knitting, either by turning at the end of each row or by using end caps on one side of each cable. So for most projects, there's no need to buy straight needles anymore!

Flat knitting with circular needles (source: KnitPicks)

Interchangeable needles are great because, as the name suggests, you can mix-and-match different sized needle points with different lengths of cables. Ever the cost-conscious shopper, I originally purchased the Boye's Needlemaster set using a Michaels 40% off coupon, but unfortunately I discovered later on that their cables are thicker and harder to use for the magic loop technique (a method of knitting small, tubular items like socks). Instead, I now rely solely on my Knit Picks Options Interchangeable Nickel Plated Circular Knitting Needle Set. The cables are thin and flexible, the metal points are sharp and pointy, and the price is very reasonable for what you're getting. If you want to go cheaper, they offer an acrylic version, and if you need an unusual size or length not available in this kit, you can purchase fixed circular needles and individual cables to fill the gaps.

Knit Picks Options Interchangeable Circular Knitting Needle Set

2) Double Pointed Needles (DPNs)
DPNs are also commonly used for knitting in the round, but for smaller diameter patterns such as gloves and socks. I tend to like longer length DPNs since the knitted loops can easily slip off either end of the needle.

Knitting in the round with DPNs (source: Purl Bee)

 As usual, sets are the cost-effective way to go, which is why I bought Knit Picks 6" Nickel Plated Double Pointed Knitting Needle Set. And for larger or smaller sizes, you may have to buy them individually.

Knit Picks Double Pointed Needle Set

Anyway, that's just my experience when it comes to buying the bare minimum of needles, unless you're Sophia and happen to have a grandmother-in-law who wants to bestow her lifelong collection to you. :)

Question:
If you knit, what needles do you love and recommend?