I would think about the likely market for your house. As Calendargirl says, if it’s likely to be a retiree, then a shower could be the best bet. A single person might (or might not) feel the same. If it’s a family house though, I would assume that having no bath would put people off. House prices being what they are, I don’t think that everyone will have the budget for major refurbishment soon after moving in. I wouldn’t have considered a house with no bath when we bought ours, and the children were 5 and 7.
I don’t think many young parents would want to use a baby bath in the shower. Apart from storage issues and ‘tin bath in front of the fire’ connotations there is the fact that toddlers and small children still need to be bathed and wouldn’t fit.
Is there room for both? If at all possible I think that would be the preferred option, but I prefer baths and am in the process of having my bathroom refitted with a new one (and a new shower). I realise that the day will come when it won’t be used, but for as long as I can manage it I want to keep the option of a soak.