It's really just going to come down to a matter or preference and what you would rather carry. Rather than espouse the benefits of a fixed blade, let's just look at the downsides...
-Unless your sheath is attached to you, it gets a little cumbersome keeping track of both the knife and sheath
-In some areas (urban envrionments, office places etc) a fixed blade knife might be seen as a weapon
Past that, you're not really left with a lot of disadvantages. So unless you just really like the convenience of one-hand-opening and one-hand-closing folders ( I have to admit I do kind of miss them ) then chances are you will prefer a fixed blade unless these other limitations prevent you from carrying one.
I think it's a bit obvious to go on about their advantages, but maybe they're not obvious to everyone so...
-Cleaning is a breeze. Wipe the blade off, dry it--compared to cleaning out all the confined spaces on a folder this is a breeze
-A good solid feel. A fixed is inherently stronger than a folder, but even the most robust folders often times have enough "flex" to them to feel a bit filmsy--a fixed is a rigid piece of steel
-No mechanical failures of any kind--about the only thing that can open is your sheath losing retention.
I just like working with a fixed blade more than a folder, and if all of my limitations allow me to carry a fixed that's what I'll carry.
Edit:
Oh, yeah, and I forgot to mention I carry the Izula. It's a fantastic little knife... So much better than it looks, believe me. When I got it I thought, "Did I really just spend $50 on this thing?" but then I started using it and I was amazed how such an unassuming little knife could be so great.