I just can't see the appeal of the others, I mean you do have a big tool box after all. To me, a tool cart is supposed to be something very light and very easy to move around. If its full of tools well... maybe not so easy.
Depends on the situation.
I have a large tool box, but can't bring it to work because there really isn't room. If I did clear the room for it, it would be blocked in within an hour or two.
A small cart just isn't going to be able to hold what I need.
So, I have to settle for somewhere in between. I have the hf red 5 drawer with the side drawer bank attached. I have it pretty well packed with tools.
Yes, it is a little cumbersome to move, but possible - my big box would not be.
Another mechanic works out of the black hf box. Its easier to move and takes up less room. He is in my box several times a day mainly because his can't hold enough. The other two people in the shop (owners/transmission) builders also get tools out of my box, but not as often.
Another reason for a cart these - is speed. Most, I would say 90%, of what I need on a daily basis is right there on top, either on a magnetic holder of some kind, or laying in the open spot, plus a few racks of portable sets.
Its also handy for inventory. At a glance I can see if most everything is in its place at the end of a job and not forgotten somewhere.
I come in to work earlier than the others, and also leave earlier as well. So, first thing in the morning I have to take inventory. Rare is the morning when all my tools are where they belong.
In a perfect world none of this would be a concern. Each of us would have our own areas with a lift, better yet, two lifts and a open bay or two plus the areas outside in front of the bays for quick stuff.
But we just don't have that kind of room - I'm guessing most shops don't. Most of the ones I've worked in didn't.
You end up having to go from one end of the shop to the other, we try to minimize that, but you have to work around lift availability, type of job, parts issues, and unexpected surprises. (The engine they delivered isn't the right one, the head is cracked and we need to find a good one, trans case is shot have to find a core, etc....)
So, bringing the work to me just isn't functional.
Bringing a large 'regular' tool box to the job isn't practical or even possible much of the time.
Even if I had room somewhere to shoehorn my big box in and not have it blocked constantly, I still wouldn't care to try using a small light cart I would have to load up for every job.
I suppose there are people who can off the top of their head know every tool they will need to pull the heads off a 2000 intrepid 3.2, then while the heads are at the machine shop, unload and reload the cart for a water pump on a Volkswagen 2.0 turbo, and then unload and reload to start pulling the engine on an '06 maxima. Which is what I'm doing today btw.
Then when the heads get back, unload and reload for them, plus the waterpump/timing belt, finish that and then back on the maxima. Plus figure a couple other odds and ends are going to pop up, crank/cam sensor, alternator, trans service, or what have you.
I could remember most of what I need probably, especially for the maxima since I did one of those engines about 3 mts ago, longer for the heads though, even longer for the Volkswagen waterpump.
Sure, most of the tools will be the same, but enough different I can guarantee I would be making a lot of trips back and forth if I tried to use a smaller cart.
Hell, the guy who has the black hf cart has to make several trips a day to my box and he has his packed.
Oh, and then its entirely possible the other mechanic might get a break and start pulling the max engine, and then have to put a trans back in and I have to finish the max, or I might end up starting and staying on the max while he finishes my heads, or almost any combination imaginable. We each do things a little different, not a big deal, but I'm sure it would add some more trips to and fro if I tried to use a little cart.
So, my overloaded 'cart' is an imperfect solution for an imperfect world, but its the most functional I have found.