As a quick summary of the methods:
1. Computercraft - easy-ish to set up (many scripts require a GPS system, the chunkloaders canbe a pain to make, etc). When it's made, a combination with an enderchest makes it quick and easy to move around, and it doesn't destroy the landscape too much.
2. BC Quarries - There are basically 2 states to this. Before you have a glut of BC power, they are quite expensive, and can be a bit fiddly to run (you can use biomass or fuel, or similar for a decent speed, with the issues associated with those methods). It'll easily dump out into an ender chest/tesseract. After you have a glut of power (boiler+tesseract, for example), these become really powerful. You can sketch the area with landmarks, put down the quarry, put down the energy/item tesseracts and leave it to go. Full speed it goes VERY quickly too.
3. RP2 Quarries/tunnel bores - These are, potentially the quickest auto-miners in the game. The blocks/sec depends almost entirely on how you build it. They are quite resource-intensive to build, but tunnel bores can just be left running without any real issues.
4. SC2 - These are a bit niche, the setups can be finicky (you need to sort the tracks, cargo managing, etc.). I wouldn't put it at early game (like the CC method), but later game, it's simply outclassed.
5. TC3 Bore - Visually stunning, doesn't require any power infrastructure. But, it will decimate the environmental flux, and runs through tools incredibly rapidly. Similarly niche, like the SC2 method.
6. IC2 Miner - If you have a decent power-gen system (geothermals are good for this), these are really powerful early game. Fully upgraded, it'll miner faster and with more precision than the CC alternative, although is a little more difficult to relocate. I've been tempted to try the IC2 miner frame machine at some point.
