Re: Delay in front of an amp?
I prefer it throught the loop, but both my amps are high gain. It does a lot better into cleanish amp with a pedal before it for dirt. Even a TS, Delay, Amp is better than running it into a full bore gain monster. Also, I find delays with softer 'analog' style repeats do better in front of an amp too.
The other thing is, depending on your style, you may want delay into a distorting amp (shoegaze, ambient, noise rock/pop, etc.)
The argument that delay was around before loops is true but not true. Didn't digital delay come about around the same time as high gain and effects loops? So if you're running an echoplex into a Plexi, that's vintage correct, but running a DD-6 into the input of a Rectifier or 5150, is obviously not the same thing. Not to mention, in the early days of delay, how much was added at the board (same sound effectively as in the loop) so you don't get the smearing sound?
Finally regarding reverb, I believe any pedal will sound bad into a distorting amp. Turn it on for cleans, then switch to delay for gain sounds.
Just my thoughts and experiences, others will disagree. Find what works for you.