I recently bought some Tamiya 1/48 scale figures,and I noticed a significant proportional difference between the newer Tamiya 1/48 offerings, and the old Bandai kits. Which one is closer to true 1/48 scale?

Well, you could measure them and establish which match reasonable human proportions?

Hi, I would say go by quality. So, Tamiya would be the way to go. The Tamiya's are a little on the thin and small side usually. However, some of the newer ones in the vehicles come with a little bulkier clothing and proportions.
Personally, I prefer to go resin to get crisper detail and use the weapons and gear from the Tamiya sets as they are perfect to scale. I've seen some people do great/fantastic things with the Tamiya figures though. Overall, there can be found a wide difference in size of figures in 1/48, but that is normal in the real world too, so match as you like. HTH

True, Tamiya's figures are much more delicate in proportion, compared to the Bandai figures, but better sculpted in most cases. I agree that people come in all different sizes, so mixing them up as it suits one, is a sensible suggestion. I like the idea of resin, but there's just not that much out there yet, although new stuff is coming all the time.

Steven, just to be sure you know, check Track48.com as they have the largest 48th scale gallery and wide range of products like figures

Thanks Greg! I was trying to remember which site it was that had all the figures.