As to the title there is no real correct answer its something you will have to figure out as personal taste use and affordability are always going to be different we all have different jobs hobbies and live in vastly different environments what works. It’s all about what your need is to which knife to buy many people carry multiple knives to suit all different types of conditions and uses.
Also looking up what the legislations are in relation to carrying knives in your state because of variations between the states and territories QLD being one of the stricter states in Australia, public places was brought up as it is an offence to carry a knife unless you have a legitimate lawful reason for carrying say for work, camping, fishing etc one stipulation that was made very clear throughout (self defence is not a legitimate lawful excuse to cary) to be clear on the laws that pertain to you simply look it up so you know where you stand.
Knife Types
Fixed blade knives: Easy to clean/maintain Usually larger but fit for more rugged and dirty jobs ie. hunting skinning animals where applying greater force to the blade is needed
Fixed blade knives are ideal for small to medium work and are generally designed for applications where a lot of force will be put on the knife. These knives come in all sizes from small skinning knives to large size knives and military / tactical knives. Most fixed blade knives will come with a belt pouch and ideal for hanging from a belt. Having a fixed blade knifes gives you a lot more control and precision. That is why most or the skinning and filleting blades are fixed. Also with the increased tang they are a lot more durable https://www.eliteoutdoorgear.com.au/product-category/knives/fixed-blade-knives/?orderby=price
Folding knives:
Folding knives are ideal for people who may need to use a knife but do not want it exposed on the outside of their clothing. Folding knives come in many sizes from tiny pen knives that will sit at the bottom of your pocket to larger folding tactical knives with pocket clips ideal for clipping inside the pocket. Most folding knives are designed with liner locks to stop the blades from closing on finger during use so if you are intending using a folding knife for lots of heavy use ensure it is designed with a liner lock. Folding knives are very popular throughout many industries and general population. They are really handy to have in your pocket for every day carry (EDC) where you do not need the knife to perform a single task that it is designed for but want a knife that can achieve great quality over many different applications. https://www.eliteoutdoorgear.com.au/product-category/knives/folding-knives/
Locking mechanisms:
Liner locks are very simple and reliable easy to maintain as there is no real moving parts to it, a section of the knifes liner is cut out and bent inward acting as a spring to lock the blade in place when open and many manufacturers are using a detent ball which securely holds the blade in the closed position and it gives it a nice snapping feel when closing the blade.
Serrated blade:
Having a solely serrated blade give’s a limited range of use although works extremely well for the jobs they are intended for such as diving, boating ect the spiderco Dragonfly2 which uses H-1 steel that doesn’t rust which is great for harsh environments such as salt water these knives slice through rope, clothing, fishing line and seat belts with minimal effort in a situation where you may be tangled up under water or in a car accident the quick and effective cutting action may make all the difference. https://www.eliteoutdoorgear.com.au/product/spyderco-delica-4-lightweight-black-serrated-blade/
Straight blade:
These are the standard shape that is useful in most situations there are many other blades out there they do tend to be more specialized for certain purposes all with there own unique trade offs. Reasonably strong and an all rounder shape that is good for slicing/chopping with a thicker blunt back edge for applying greater forces and a good strong point for penetrating https://www.eliteoutdoorgear.com.au/product/morakniv-bushcraft-black-carbon-knife/
Multi Purpose:
These blades are a split with the tip to the middle of the blade being a strait edge and from the mid to the handle being serrated, This style of blade is perfect for someone looking for a first knife and for anyone that will be performing a vast verity of work with the blade these would be one of the most popular blade configurations as the serrated devours rope and textiles with ease while still having the precise cutting of a strait blade. https://www.eliteoutdoorgear.com.au/product/gerber-prodigy-tanto-green/