L'Oréal Paris Superior Preference is a classic formula that remains popular with users because it's easy to use and the colors are fade-resistant -- they last up to eight weeks. The formula uses a traditional squeeze tube applicator with an extended tip that easily reaches roots. It comes in 53 vibrant shades that look natural, according to reviewers.

Reviewers say Clairol Nice 'n Easy Root Touch-Up does an excellent job of covering up gray or natural roots. It blends in flawlessly with color-treated hair, to buy you an extra two to three weeks between hair colorings. It's available in 22 shades, with an online tool to help you match hair colors from other brands.

Clairol Natural Instincts aces professional tests -- and earns loyal followers among users -- thanks to its glossy, fade-resistant color. It's a demi-permanent formula, which is gentler than permanent hair color but lasts longer than semi-permanent ones (through 28 washes, Clairol says). Reviewers say it leaves hair feeling soft and has a pleasant fruity scent. It's available in 33 shades.

For concealing roots on-the-go, expert testers prefer Color Wow Root Cover Up powder. Packaged like an eyeshadow with a brush, Color Wow's charged particles cling to hair (not scalp) and won't wash off until your next shampoo. Unlike other root concealers -- sprays, markers and waxy crayons -- testers say Color Wow isn't messy or obvious. It's available in seven shades.

Highlighting your hair at home can be tricky, but users say Revlon Color Effects Frost & Glow truly delivers salon-like results. It's available in two shades (for darker or lighter hair) and comes with a pull-through cap that allows you to highlight just the strands you want. Users say the ammonia-free formula is gentle on their hair.

If you'd like to color your hair and add highlights too, reviews say L'Oréal Paris Couleur Experte is your best bet. Each box includes a base color (there are 15 shades) and a coordinating highlight color. It's a two-step process -- first you color your hair, then you paint on highlights with the included fingertip brush -- and experts and users say the results look fantastic.