I like fixed blades and my Leatherman (Charge Ti) but my issue is with ease of carry and weight.

My favorite knives:

--Ritter Mk2 (fixed): 12.8 oz -- belt - or bag - only
--Leatherman Charge Ti: 8.4 oz -- belt is best, big for clip
--Ritter Mk3 (fixed): 5.7 oz -- belt only
--Ritter Mk1: 3.82 oz -- good clipped, big for EDC
--Ritter Mk1 mini: 2.68 oz -- my EDC

Of course a lot depends on your own circumstances.

At home and around town (suburbs) my Mk1 mini does everything I need. If I need pliers, a screwdriver, or whatever, I get them out of my toolbox. If I have car troubles, well, a Leatherman isn't going to fix my car. I call a tow truck.

When car camping I ALWAYS bring along both a fixed blade (usually my Mk3). It gets used a lot - cooking, fire prep. I ALWAYS bring the Leatherman, but the LM doesn't typically get used much. I also always bring a saw (bow or folding) and an axe (I prefer a long handled axe). One of my Mk1's was always clipped on my pocket.

I don't backpack anymore, but when I did weight was everything, so I typically only carried one of the Mk1's clipped.

For survival, well, consider me in the "a survival knife is the knife you have when you need it" camp. I carry minimal gear and dress for potential weather. I like Peter Kummerfeldt's view of survival gear (see outdoorsafe.com)

I carry a PLB and bring the minimal gear needed to survive until rescue. A knife is going to have to help me stay dry and warm while I wait. It will cut things - smallish things. It won't split wood. No snares. No building log cabins. At most it may need to cut small saplings, which my Ritter Mk1 mini has done.