Overall a vegan diet has been shown to be the healthiest (as long as you eat a variety of vegetables), with a high oily fish/nuts diet coming second, closely followed by vegetarian (with variety, but dairy and eggs). Unfortunately a meat based diet consistently comes out worst for us.
Vegetable protein is just as good as meat protein as long as you eat a wide variety (to ensure you have all the essential amino acids). Your body can absorb the protein from vegetable and animal sources equally well.
Whole lentils (eg green or brown) have the same protein content as steak.
Split lentils, beans, peas, tofu, sprouts etc have the same protein as most fish or chicken.
Tofu is very versatile and can be turned into anything from milks and sauces to solid burgers. Explore different techniques online. Tempeh is a little less versatile, but very healthy. Give it a go.
Quinoa, buckwheat and amaranth have a little less protein than fish, but not much.
Tinned beans and lentils are easier but dried are cheaper. You need to soak dried beans overnight and then cook before eating.
Sprouted lentils and beans are good sources of protein and can be eaten raw or used in cooking in the same way as other beans.
Mushrooms contain some proteins not found in other vegetables. Eat at least twice weekly.
Nuts and seeds are good protein and also healthy fats. Eat a wide variety in moderate quantity.
Oily fish and seafood appear to have some heart and brain protective effects (more than taking a supplement). They are also high in B12. The best oily fish in NZ are: kahawai, mackerel, salmon, sardines, pilchards, anchovies (but watch the salt).
Eggs are animal protein, but are more nutritious than meat. Ideally you want to avoid eggs, but they are better than meat if choices are limited.