[HesNot]

This is a tough one - so much depends as noted on what amp you're using and what sounds you're trying to achieve. In HS I only had an amp and one pedal (Roland JC50 and a Proco Rat) - but the amp had built in chorus and reverb. In college I had an amp and two pedals - a Peavey Renown 100 and an Ibanez TS10 and Boss CE2 - the amp had reverb and an OK overdrive channel although I often used the TS10 into the clean or into the gain with the amp set to a low gain). Later I had a Twin Reverb and the same two pedals which worked just fine. But that was driven by the kind of music I was playing at any of those times - lots of 80s/90s alternative - not a lot of high gain stuff - so the chorus was pretty key and an overdrive to get crunch was key.

Currently - hmmm it's a tougher question - one pedal it would probably still be an overdrive - in my case a T Rex Moller that has a gain and clean boost built into one pedal and allows me to blend wet and dry signals - works well with both my amps and gives me a lot of options.

If two:

T Rex Moller and
TC Electronic Flashback delay - the huge range of effects can get a reverb ish sound for the amp without reverb - slapback - tape and reverse and classic digital plus the TonePrint library