Can a creature with Flying block a creature without Flying?

Yes. Flying only restricts what can block the flier; a creature with Flying can block any attacking creature, whether it has Flying or not.

Does reach let a creature attack as if it had Flying?

No. Reach only allows a creature to block fliers; it does not grant evasion and does not let the creature be blocked only by fliers when attacking.

What is the best Flying card?

By popularity, Flying is among the most-played Flying cards — see the full ranked list above.

Best Flying cards in MTG

Flying: A creature with Flying can only be blocked by creatures with Flying or reach.

Flying is one of the most reliable evasion abilities, letting your creatures connect for damage turn after turn against ground-based decks. Build around cheap, efficient fliers in aggressive decks, or use a few large fliers to close out control matchups. Remember that fliers can still block ground creatures, so they pull double duty on offense and defense.

FAQ

Can a creature with Flying block a creature without Flying?: Yes. Flying only restricts what can block the flier; a creature with Flying can block any attacking creature, whether it has Flying or not.
Does reach let a creature attack as if it had Flying?: No. Reach only allows a creature to block fliers; it does not grant evasion and does not let the creature be blocked only by fliers when attacking.
What is the best Flying card?: By popularity, Flying is among the most-played Flying cards — see the full ranked list above.