I have a right mix.
I keep a Halfords set in the truck, because for £100 it covers everything I'm likely to need, and it doesn't matter much if I leave it at the side of the road. And yes, I have done that.
I have Halfords Industrial rollcabs and topboxes at home and work. The get both for £400 deal is how I bought the work set; the ones at home were £100 each as ex-display. I have Britool step-up box at home, which is the same size and adds 4 more drawers.
I have Snap-on 1/4 and 3/8 sockets & ratchets in my box at work, plus 8 to 19mm spanners. Most of these were bought as promotions or secondhand; normal prices are extortionate. The ratchets are well used, as I've 'found' them over the years. I do find the basic SO tools to be excellent, but that is the absolute minimum that is acceptable considering the cost. I can't imagine ever spending the money necessary for SO boxes, and I cannot see why anyone would buy them without the tools to fill them. We no longer have the rep turn up at work, so the 'easy to warranty' doesn't really apply.
SO ratchet screwdrivers are the only ones I've found worth having, and have 3 sets; one for the truck, one for work and one at home. This is probably extravagant, but it's only money.
I have a load of Sealey stuff, which is pretty good, well priced and easy to find. Plus they do all sorts of special stuff, which tends to be much cheaper and just as good as SO equivalents.
I also have a load of unbranded stuff for odd jobs; like bearing pullers, brake windback tools and the like.
As I go to several shows each year, I often buy from traders, so I have lots of Eclipse pliers, saws snips etc, none of which were more than £5new. I once bought a number of Bahco files and handles, and got some funny looks at work when I on burnt the handles as they'd never seen that before!
I do find that it is worth buying branded cutting tools, like files, chisels, saw blades and snips.
It is also worth keeping some cheaper spanners for modifying to do awkward jobs, as heating and bending a £15 SO spanner really hurts!