I've played the SLO and the VH4 a lot in recent years. I borrowed a friend's 101B for a while, but I didn't feel like I needed to own one. It is a very versatile amp that does a lot of tones well, but there wasn't that ONE tone that knocked me out.
The VH4 I used to be a big fan of, but now I've kind of fallen out of love with it. I've tried it with EL34s and 6L6s. It's a little compressed, and a bit dark and stiff for my tastes these days. Still a great amp with great features, but not really my thing anymore.
Of the three amps listed, I would go with the SLO. The overdrive channel is killer. And this amp is not a one trick pony to me. The clean channel with the crunch and bright switch engaged, with the gain at about 4 or 5 is really great. If you're looking for pristine cleans, then yeah, the SLO is kind of sterile and blah sounding. But if you're looking for some nice semi-clean, mild crunch kind of tones, it can do that pretty damn well.