Re: Boss Pedals. The good, bad, and mediocre.
I'm not really a Boss Drive pedals type of guy, but what I've owned and played, the Dual Overdrive (SD-2 maybe?) did have a decent tone, the red channel was a bit fizzy, but the green channel had a nice bit of breakup.
The OS-2 was the biggest pice of crap I owned. It was my first pedal and biy did I choose wrong.

It was like it could decide if it was an OD-2 or a DS-1, so it tried to do both poorly with a scoop control. One of the only pedals I've ever sold.
The MT-2 is the staple, go-to pedal for the young crowd playing metal. Everyone knows it, what more can you say. I'd like to hear a modded version, I bet it's pretty nice actually.
Fuzzes:
FZ-3 is an interesting take on fuzz, it's very "safe", verry Boss. I bet the FZ-2 was way too wild and over the top (octaves and harmonics, I'd love to get one) so they backed it way down on the FZ-3. I prefer the Tweak Fuzz in the safe fuzz category, but it's always nice to have unique tones available.
FZ-5 is the new modelling Fuzz, the Fuzz Face model isn't bad, it's no Analogman or FoxRox, but it does do a nice, gnarly fuzz. The Octavia and Maestro settings seem like characatures of those pedals, not accurate models. A real octavia is a bit harder to use, but you'll never get the Boss to sound like a real one. Same goes for the Maestro, they modeled it to sound like an over the top, Satisfaction tone. I guess it's fine to play that, but I find it really thin compared to the Fuzz Face mode.
Delay:
DM-3 is one of my top delays, it's got a great, warm tone, and it's the best oscillating delay, bar none. The only two wishes I have for it would be more control in the low end of the repeats area (you get 1 or 5) and a little longer time for my playing style. The DM-2 is great too, it's the darker cousin of the DM-3 which is a little crisper in extended repeats.
DD-3 great basic delay pedal, although it's too sterile for my tastes. If you want a crisp digital delay, it's a solid choice. I think the DD-20, DL-4 and Echo Park are much more versitile, and sound better, but they cost more too...
Modulations:
HF-2 Hi Band Flanger is one of my favorite flangers. Where the BF-2 is a bit overbearing for me, the HF-2 is light and airy. Great for clean and gain, you can actually hear the guitar instead of only the flanger. I wasn't a fan of the BF-3 for the short time I tried it.
I'd love to try an old PH-1r, and I'd also like a Dimension C, and the old stand-by, CE-2.