If you look carefully, you can get a used SB26 for about sixty quid (the one I got yesterday was fifty, from a used camera dealer). That's about the same as a new Yongnuo unit and I'd take a fifteen year old SB in good condition over a brand new eBay special any day. The SB26 was introduced in 1994 and discontinued in 1999 and cost over two hundred quid. Anything that went for that sort of money over a decade ago was hot stuff and built to last!
The reason I like them so much iis that they do all the things that strobists like (full manual control, PC synch, zoom, swivel and so on) and they have a built in optical slave. That's not so uncommon, but it's damned useful because it cuts down on the number of triggers you need.
But the best bit is that they do something that no other flash can do. Seriously, I've looked - this is unique. When you use manual optical slave, you usually have to set all your flashes on manual optical slave. You can't start mixing and matching iTTL and manual or your manual flashes will go bang too early. The SB26 is so useful because it can be set to slave mode with a delay, so it will ignore the monitor pre-flash from other units and only go pop when the main burst is fired.
Which means it's an absolutely perfect background, fill or separation light because you can just wedge it somewhere or sling it on a stand and let it do its funky thing.