I searched everywhere couldn't find anything that answered my questions so here I go:

Which one is the best option for recording guitars, direct input or micing the amp ?
depends.... probably the micing the amp since the sound come directly from the amp.. unless u have some fancy thing for ur line in.... but i could be wrong
I play guitar.
most professional recordings use mic'd amps. the only real practical application for using a direct input would be if your running any type of programs on your computer for your guitar, (amplitube, revalver, etc.)
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a lot of professional recordings will do both actually, the benefit of this is that you will have a completely clean take that can be reamped later if necessary. Although yeah the finished product will almost always be recorded froma miced amp, it generally sounds better.
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You might get a usable clean tone using DI but gain/distortion usually sounds much better mic'd.
Epi Les Paul-APH1/Mean 90
MIM Strat

Korg DTR1000
Mesa/Boogie Quad Pre
Mesa/Boogie Midi Matrix
<power amp>

Quote by rhcp_freak
If you're EQ'd loose, you'll sound loose anyway.