....because they are all relatively inexpensive and I like to play with a clean Fender amp boosted just a hair with a TS9 for my base tone. Stacking the Fuzz for solos with a bit of guitar volume rolled off howls perfectly, and the DD7 can add a bunch of different flavors for some variety (including short loops and a very decent analogue simulation).
Caveman overdrive - base dirt with a boost for lead is perfect and can be done by a bunch of dual drive boxes (BADCAT Siamese drive/box of rock/Route 66/vs-xo) I am just digging the caveman a LOT right now.
Visual Sound Dual Tap Delay - because stacked, beautifully clear and easy to use delay is AWESOME. I know the timeline and a bunch of others get tons of hype, but simple straight forward and easy to use is the best.
Digital Reverb - boss RV5 is great and gets most jobs done.
With a decent amp, there isn't much you can't cover with all that!