Which package of TNY287 has lower RTH(JA) in our layout?

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We have designed a 5W, 24V Offline Flyback SMPS (240VAC input).
We are using a TNY287 controller which also comprises the switching FET.
There are three different package types of the TNY287.. the SOIC8, PDIP and ESOP.

We do not have room for a heatsink. As such, we are wondering which package will have the best thermal withstand, the PDIP, or the ESOP?

We realise that the ESOP has the lower Rth(JA) figure. However, that Rth(JA) figure (from pg 12 of the datasheet) concerns a single sided PCB. Though we have a double sided PCB, and so we suspect that the PDIP will actually end up having the lower RTH(JA) value, since the PDIP has metal legs which go right through the PCB, and get soldered to thermal copper pours on top and bottom layers.
So do you agree, that in our case, the PDIP will have the lower RTH(JA) value?

Please find attached the view of the layout with PDIP, and then with ESOP (red is top copper, blue is bottom copper)

TNY287 datasheet:-

첨부 파일Size
TNY287_ESOP.jpg218.53 KB
TNY287_PDIP.jpg192.55 KB


Thermal impedance mentioned in the datasheet was based certain copper thickness and area. So as the thickness of copper and/or area increases, yes Rth(JA) will become lower.