What's the best method for jump point defense?

[Garfunkel]

Box launchers combined with spinal lasers and/or particle lances a good combo if you're serious about defending the JP itself. Bremen already explained the reasons pretty well. And use FACs instead of actual warships because they are cheaper and faster to build and require fewer maintenance modules. The type with box launchers doesn't need to be fast.

You said the system is barren but if there was a rock somewhere, you could plant a mini-colony on that rock with an Orbital Habit and actual maintenance facilities. That would mean you don't need to build a huge station with an entertainment module and that you can produce MSP on site as long as there are minerals. If there are any minerals in the system then this method is the best one as you can rotate the vessels between the colony and the JP. Then you can add STO units on the colony as well.

[serger]

I use fast monitors for static defence agains superior enemy (max-forced drives, small fuel tanks, 1 axial or lance, several quick-firing beam cannons and small MW, minimal armor and shielding; tug them to the point once for 4-5 years or use station) with aux cutters (1 minimal MW + optinally 1 minimal RG).
Beam light cruisers (non-forced drives, decent fuel tanks) - to block critical frontier points temporarily.
Several times there was squadrons of battlecruisers (more fuel, armour and shielding than monitors, still the same fast damage-dealer focus of design) to block very critical frontier point, but it's not my preferable tactics.

[Michael Sandy]

The "best" method is early detection.  If you have sensor outposts at all known jump points, then you will get early warning that something is coming.  And sensor outposts can be commercial, which means you don't need to worry about maintenance lifespan.  You can drop them at every jump point and mostly forget about them.

I second the forward defense strategy.  Being able to withdraw from a box launcher volley, and withstand anything smaller, while having your own box launchers means that almost no matter what, you will inflict outsized casualties compared to your size.  It also preserves that asset that is most important to you, the ability to transit INTO that system safely.