First off, I am a locksmith. Have been for twelve years. I know exactly how all of these locks work.

NEVER use WD40 on any lock EVER for the purpose of lubrication. It is meant to be used as a water displacing cleaning agent. If your lock is seized, rusty, grimy, old, horribly gunked up........use WD40. spray, wait 5-15 minutes, whack with a mallet or deadblow hammer (or hammer if you don't mind scarring it up). Try your key. Repeat. Run the key in and out rapidly many times. Repeat these steps. If your lock still refuses to open, buy a new one.

Use any TEFLON based lubricant (tri-flow is what my industry uses, almost exclusively) on all locks for routine lubrication. These work better than anything out there, including 3-in-one oils, household oils, and machine oils. You should lubricate your locks at least 6 times a year. More often in bad weather, especially on bike locks which tend to get a lot of road particulates in them. Spray some tri flow into the keyway and on all other moving parts/surfaces. Run the key in and out, and turn back and forth several times to work the lubrication in. This will exponentially prolong the life of your locks.
Believe it.

I also use tri-flow to lube my chain frequently (almost daily). Just spray on, turn cranks or freewheel, wipe off. It is great stuff.

As to ON GUARD locks vs. KRYPTONITE.
I have seen more lock failures with the on guard brand than the kryptonite. In fact, I have never had a customer bring in a kryptonite lock that was broken in any way, only to have them removed from bikes, or keys made.
They function almost identically, and can be defeated in exactly the same ways. So neither is more secure than the other in my opinion. However, the kryptonite brand locks DO SEEM to be built quite a bit more robustly, with tighter tolerances and cleaner machining. I own two of them.

So, for lasting, quality operation, I go for the kryptonite over on guard. It is best, IMO, to invest a little more cash into your locking system.

Best lock of all out there would be a kryptonite NYC chain with a heavy duty grade 1 MUL-T-LOCK padlock. Not very convenient, rediculously expensive, and perty dam heavy though.