My preference is probably for coins struck before Christ although I'm fairly open-minded on that. I suppose I'm looking for coins that have both intrinsic and historical value, are well made, can be clearly dated and/or authenticated with perhaps an interesting history of their own (maybe a short-lived or little known Emperor, etc).
Going back in time a little further, I'd also be interested in coins struck for the Greek/Ptolemaic period of Egypt after the conquest by Alexander the Great in 332BC as they might have both Greek and Egyptian iconography on them and perhaps be minted in Alexandria.
I'd be surprised if there are many Pharaonic coins around but perhaps some survive from the later dynasties of ancient Egypt? These I'd be especially interested in as they'd probably only display Egyptian iconography and I'd be very curious if you came across any of these.
But like I say, I'm quite open-minded, so if you found any old coins, especially if they have a reasonable metal composition and content or happen to look particularly good or have an interesting background, please feel free to let me know here or directly by PM.
Thanks very much!