My advice is decide which one you want to fly once you have your licence and then train on that one.
How do you decide which one you want to fly post-PPL training?
Interested about the equivalence in cost - from where I am the R22 will be less expensive than a Bell 47. Wherever you are, I would have thought that operating costs of an R22 will be less than B47
What do you want to carry with you?
If it is more than two moderate people and tooth brush, this favours 47
How much do you weigh?
If you are heavy and want to fly with other heavy people, the R22 will have zero/limited endurance
Do you actually want to go somewhere (Cruise speed)?
R22 is significantly quicker than B47
Are you going to mix fixed wing & rotary once you have both licences? (In fact, I bet you end up doing more rotary, unless you have long trips to make)
If you are, then be particularly careful about keeping REALLY current in heles (engine failures) AND favour the B47
If you will want to fly/hire from various locations there will be much more choice of R22s than B47s