Siblings in JBL's Studio Monitor series, so they share a family sound. It comes down to size, output and price.
| Area | Better | Why |
|---|
| Bass | B | JBL 4329P digs deeper - 28Hz against 45Hz. |
| Built-in power | B | JBL 4329P has the bigger amplifier (600W vs 300W RMS). |
| Connections | evenly matched | The same set of inputs and streaming options. |
| Size | depends | JBL 4305P is easier to place; JBL 4329P is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | JBL 4305P: a sub output; JBL 4329P: a sub output. |
| Price | A | JBL 4305P is cheaper - $2,200 against $4,500, about 51% less; arguably a different class. |
A JBL 4305P B JBL 4329P
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
The usual trade-off: JBL 4329P measures better, JBL 4305P costs about about 105% more% less. Whether that gap is worth the money is the call only you can make - and in a normal room it is often smaller than the numbers suggest. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 45Hz anyway, which makes the cheaper JBL 4305P much easier to justify. In a large or open-plan room, JBL 4329P has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, JBL 4305P is the easier speaker to get right.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.