I'm really struggling here. I mean, I've got plenty of tools I wouldn't be without, and some that I even consider to be reasonably decent, but I don't really think of them as delightful. We can safely rule out anything which runs software on general principle[1]. Cutty things that work well (be they wire cutters, kitchen knives or planes) are natural fit for 'satisfying', but I'm hardly a blade enthusiast by forum standards and my skill with a plane is borderline[2] non-existent. "My bicycle" is too obvious.
I've often felt that I ought to own a proper Avometer, but the truth is I'd still reach for a digital multimeter the vast majority of the time.
Soldering irons? I grew up with 12W mains powered crap. I can solder 60:40 with pretty much anything.
'Scopes? I rather like my Goldstar 50MHz analogue-with-digital-storage jobby, though I suspect that's mostly because I bagged it for 100 quid on eBay before the DSO revolution really got going, rather than it being particularly special. My cheap Rigol's a better tool in every way that actually matters, but it's still an unsatisfying computerised toy rather than the sort of thing I lusted after when first learning electronics.
Software aside, I should put in a word for the humble Garmin. I'm old enough to not take GPS for granted, and that something so powerful is affordable in a package that fits in the palm of your hand is barely distinguishable from magic. It's easy to forget about that when you're bitching about UI bugs and routing algorithms, but not so much when you're standing on a hillside with it displaying your position to within three metres.
The Internet has changed, improved and probably saved my life. But so did intravenous immunoglobulin.
[1] ie. Sturgeon was an optimist.
[2] I put in the effort to use when making the bed frame, simply because I couldn't face the amount of sanding involved, and got better results for doing it.