A small but ingenious $5 plastic puzzle and a doll that smells like strawberry shortcake are considered two of the year's best toys.

A doll that's supposed to wet its diapers but sometimes leaks from its neck as well and the type of killer toy boxes that have taken the lives of more than a dozen children are listed among the worst Christmas gifts for kids.

And then there is the plastic oil refinery set rated as the "toy that broke the quickest," and the Brooke Shields doll described as the "ugliest" doll in the annual sorting of toys by the Consumer Affairs Committee of Americans for Democratic Action.

The ADA's ratings and a bagful of toy safety advice from the government's Consumer Product Safety Commission were distributed yesterday to help consumers get through the holidays safely and merrily.

The CPSC, launching its annual National Holiday Toy Safety Campaign, singled out toy chests that lack safety hinges as among the most dangerous toys this Christmas, as did the ADA committee. Since 1973, the chests have been blamed for 21 deaths and one case of permanent brain injury when the lids crashed down on children's necks or heads. CPSC Chairman Nancy Harvey Steorts said parents should buy only chests equipped with safety hinges -- or buy the hinges separately and install them.

Steorts also urged consumers to select toys that suit the age, skills, abilities and interests of the individual child.

"We believe injuries will be reduced if the toy is matched to the child," she said at the toy safety program, cosponsored by the CPSC and the Toy Manufacturers of America and held at the Children's Museum.

Steorts did not identify hazardous toys by brand names, in contrast to some years ago when the goverment published an unsafe-toy list. She acknowledged that some toys now in stores could pose a hazard and recommended that consumers who have a problem with a toy or suspect a problem exists call the CPSC toll-free hotline at 800-638-CPSC.

At its press conference at the Oyster School in Northwest Washington, the ADA consumer committee proclaimed Mattel's $18 Bye Bye Diapers, which comes with a bottle and a heart-shaped potty, as the most ridiculous doll of the year and Kenner's $20 Baby Strawberry Shortcake -- which blows strawberry flavored kisses when its tummy is squeezed -- as the best doll of the year.

Ann Brown, chairman of the ADA committee, said Bye Bye Diapers didn't work properly: after "drinking the water from the bottle, the doll leaked water from the neck -- which is anatomically incorrect." She also said the doll was a "tasteless" product.

Mattel spokesman Jack Fox challenged that conclusion, saying that the doll is "a real-world" doll and helpful for parents trying to toilet-train their children. "We see nothing wrong with it, nothing shameful," Fox said.

The Baby Strawberry Shortcake doll was praised for being a "nice doll even without her smell" -- a fragrance that matches the name.

Other special ADA awards were made for the ugliest doll: Brooke Shields doll by LJN; dumbest toy: A Bad Case of Worms by Mattel, and Tombstone by Ideal; toys that broke the quickest: Oil Refinery Play Set by Mego and Hot Rod Writer by Lakeside.

The best new toy of the year, according to ADA, is the $5 Gridlock Hi-Q Puzzle made by Gabriel, a hand-held puzzle whose pieces can be arranged in many combinations.

In compiling the survey, the ADA committee attended the annual toy fair in New York City, interviewed Washington-area toy merchants, surveyed more than 2,000 toys and checked industry publications and newspaper and television advertisements. From that, they chose what they believed to be this year's hottest toys and then had them tested by groups of children ranging in age from two years to teen-agers. The ADA then selected the 10 best toys and the 11 worst toys.

* The "worst" were Curse of the Cobra, Jelly Belly and Tombstone by Ideal; Dyna-Mites Oil Refinery Play Set by Mego; Glow Goop by Imagineering Inc.; Barbie Electronic Piano, Bye Bye Diapers and A Bad Case of Worms by Mattel; Hot Rod Writer by Lakeside; Brooke Shields Doll and E.T. by LJN.

* The "best" were Geomi-Trix Starburst by Entex; Power Tow Truck, Cassette Tapes, and The Magic Show by Fisher-Price; Gridlock Hi-Q Puzzle by Gabriel; E.T. by Kamar, Alexander's Star-Rubik's Revenge by Ideal, Ocean Queen Cruise Ship and Baby Strawberry Shortcake by Kenner, and Hot Wheels Inside Track by Mattel.

The ADA committee collected prices on 96 toys in 26 stores in the Washington area and found that Best Products had the lowest prices. The next lowest prices generally were at Toys 'R' Us. And the highest prices were at F.A.O. Schwarz.

Prices for the same toy varied widely from one store to another. Alexander's Star, for example, was selling for $5.97 at Memco compared with $15.95 at F.A.O. Schwarz -- a difference of 167 percent. The Brooke Shields doll was $14 at Woodies and $7.97 at Toys 'R' Us -- a 76 percent difference.

Single copies of the toy price and quality survey report can be ordered for $5 from the Americans for Democratic Action, Room 850, 1411 K St. NW, Washington D. C. 20005.