If you could only have the best, most essential pedals in front of your amp....

Jonathanthomas83

Comp - Cornish but heard good things about the FG from Thorpy. My Effectrode comp pumped like a bitch.

Drive - SS-3

Reverb - WET v1. As you want spring, I'm not a fan of that sound but Source Audio do a tidy enough spring reverb. Or alternatively get a good reverb and teen on one with the Flint.

Wazmeister

The Fat General gets a LOT of mentions here, and for good reason...

One side is maybe for the people who dont like Comps, whilst the other offers a more compressed and 'squishy' sounds. I actually own two of them; one on my home board and one on my live/rehearsal board, which is kept at our rehearsal rooms...

Wazmeister

So, for me....

- Thorpy Fat General
- RYRA Klone or Proanalog Manticore
- Duellist 
- HX Stomp

jacksparrow

Echoplex ep3

White dot Sunface nkt 275

Teese pic wah

Sola sound Dam mk11

Dam head buzz bc108

Foxrox Tzf2

Kr Megavibe.

MattBanshee

2 Big Muffs and an Akai Headrush

lukedlb

As for a comp, I used the cali76. However, the clean that I used the Cali76 to bring forth the full tone and balance the strings was actually very slightly bettered by a Ryra Klon. Naturally, the klon can also do drive, though I only think it sounds good into a Superlead; my other amps sound naff with klon drive. 
As for reverb, I’m not a fan so it’s amp reverb for me or nothing. 
So,
Ryra Klone 
Sonus fuzz into an origin effects Revival Drive
Amp reverb. 

p90fool

You will probably think I'm joking, but this;

https://www.sonicake.com/products/twiggy-blues

They're fantastic for driving the front of a Marshall, the compressor and reverb are way better than they have any right to be as is the vintage-style delay, and there's a switchable speaker sim if your amp breaks down. 

£56 on eBay.