It depends on how you use tools, what kind of soil, what kind of gardening
Spades and shovels do you use these to pry rocks and flatten boulders? If so you need the strongest shaft and head you can get. American white ash is excellent for shafts. Heads should be made from one piece of steel.
If you are a gentle user you will find heavy steel heads are tiresome. Fiberglass or resin coated steel.
A good wide step is ergonomic and makes digging easier.
Tempered stainless steel is strong and helpful if you work with clay soils that hang on and add weight to every shovel you take
Hard rakes benefit from the same materials as spades and shovels. Leaf rakes come in many different designs and I find that extra expense of these is not warranted unless you have special ergonomic requirements
Any pins, nails or screws that hold together different parts are the most likely points of failure. Fastenings should be robust. The less number of parts for a hand tool the better.
Lastly, sizing is critical for success. If the height is not suited to you back injuries can happen or you can break the tool. A spade should come up between elbow and chest height. Rakes should be around shoulder height.