Re: What do you prefer: amp or pedal distortion?
It's a very broad question really, because it's impossible to just say "amp" and describe the entire spectrum of available guitar amplification. There are some amps that sound great overdriven, and there are many others that sound like a large feral cat being disemboweled. If we're talking about the great amps, then it is difficult to match the girth and organic quality of tube overdrive and distortion with a pedal, but if we're talking about average or mediocre amps, then I've got a bunch of pedals that would absolutely destroy their overdriven sounds.
The next question is a matter of volume. Whilst there are great amps with great natural distortion, it quite often the case that they have to be played at high volumes to achieve power tube distortion, which can render them unusable in the majority of performance situations. It can therefore be the case that a pedal provides a better solution than driving an amp to the point of getting arrested. This is why lower wattage amps can also provide a valid solution, because you can attain their natural overdrive at usable volumes.
The next issue is versatility. Whilst many amps offer multiple gain stages and channels, very few excel at covering the entire gain range. Most will encounter some form of compromise, eg, providing a great overdriven sound at the expense of the clean sounds, or vice versa. Even some of the most expensive multi channel amps can be left for dead in the clean department by a dedicated single channel amp that has been designed and focused on an excellent clean sound. Many people claim that their amp can 'do it all,' but in practical terms, it is quite often wishful thinking, and when their amps are put up against something truly magnificent, they see the shortcomings of their 'swiss army knife' amp. There are a couple of possible exceptions to this, but they come with an appropriately exorbitant price tag.
Since many live situations require a broad palette of gain stages, it can be a viable option to use an amp renowned for its clean sound, and add a few good quality pedals to provide varying degrees of gain. This would depend on how important the clean sound is. If most of the music you're playing requires constant overdriven or distorted tones, it would be more beneficial to find an amp that excels at these, giving the option of using the guitar's volume to roll off for a cleaner sound when required. But if a good clean sound is required for much of your music, then the pedal option can be more attractive.
All of the YouTube clips in my sig are pedals into a clean amp. For that particular gig, I need more gain stage options than one amp can deliver. My options would be to have 3 or 4 amps on stage, or find good pedals that work well into a great clean amp. Personally, I went for the latter.
Cheers...................................... wahwah