Leaving aside that none of them have the right running gear and that's the hardest thing to make yourself the Pz 35t's turret looks marginally closer to shape, sans gun. Neither of them really looks like the real article, alas.
If you wanted a proxy I'd still opt for the Pz35t because it's more exotic looking and the Pz38 is better recognised by the average gamer so with a new barrel and a coat of green paint it will suspend disbelief better.
Actually if you want a good proxy for an Irish tank I'd look at Copplestone's 1/55 Vickers Medium C. The Irish fielded a solitary Vickers D but whats a single letter between friends?