Locks are about evidence of entry, making entry more effort than a thief thinks it will be worth, and/or increasing the risk of gaining entry due to increased time to do so.
For locks that will not break the bank, ABUS or American Lock. Personally I prefer ABUS 83 series locks (I use the 83/45 on my Pelican cases) as I can rekey them myself and add security pins (any lock smith can rekey them as well). If you just have money to blow, get Abloy locks with Protec2 keyways (or an ABUS lock with an Abloy keyway as sold by Security Snobs).
Master Locks (and about every lock sold in hardware stores) can easily be picked and does not represent any acceptable level of security. Master Locks are also vulnerable to several low tech attacks, such as shimming. Master Locks are so bad I would call them only an illusion of security, they give you protection equivalent to a generic zip tie and serialized tamper seals would honestly give better protection. Yes, American Lock is owned by Master Lock, but the tolerances are tighter and they incorporate some security features, making them harder to pick. ABUS also has tight tolerances. You can get them with a Schlage or Kwikset keyway and key them to match your house. In ABUS locks the keyway does not matter much, but for your doors Schlage makes better locks than Kwikset, so I get the Schlage keyways.
Without getting to nerdy, get ABUS 83/45 with Schlage keyway from a lock smith or a place like Taylor Security and Lock on line. Ask them to bit it with at least one #0 pin and one #9 pin and to install the 6th pin. Ask them to level the stacks, and ask if they can add a serrated pin and/or additional spool pins. While this will not give you an unpickable lock, it will be a lock that will require decent skill to pick and that will resist other none destructive attacks.
