well the term all purpose is still vage. I don't know where you live, so i have no idea what enviorment you will be in. Nor do i know your knowledge or skill level. These factors will ask diffrent preferences.
A knife to have when you need it?
I assume your mean that you will be carring in on you when your in the wilderness and not as a EDC*. Because the bushman is really not a very EDC-able knife.
I carry a Frost Mora knife with me for hikes close to civilisation. It's light, cheap and works very well. It can be more easily be broken, if used incorrectly. But having used them for a long periode of time, i know what there limits are. Very good as a practise knife also.
A more expensive Fallkniven F1 on a dangler sheath for long hikes when i really need a dependable knife that will last a lot of abuse. Did i meantion A LOT. The dangler sheath allow it to be worn on my belt, while wearing my backpack at the same time.
When i carry one of these knifes i will be also atleast carry a folding saw. A manual chainsaw is in my emergency kit. A larger manual saw and/or an axe might be carried also, depending on the situation.
I only named the two knife i'm most experianced with, because i think everybody has there own preferences and i really don't like to judge knifes, if i haven't tested and used them for awille.
If you never used a fixed blade before, i would suggest the Forst Mora line, very inexpensive, very good, easily sharpened. Build some experiance with them and choice you next knife with your new knowledge.
Don't forget to read this page of this website:
http://www.equipped.org/devices8.htm*EDC: every day carry