Choice between more flexible distance learning degree or Russel Group University

I am studying mathematics, I am currently in my first year with the OU. I have taken on all the first year modules plus a second year module (OU allowed me to do this because i have further pure maths and core etc...). I now have a choice to make;

1. Go to Cardiff university to finish my degree in Mathematics.

Cardiff is a RG university and is well admired (apparently) by employers, but my point is that from Cardiff i will be getting what i am getting from the OU.

2. Stay with Open University.

Considering i would have completed 60 credits of my second year. I will be taking a second year Chemistry module as well as the remaining Mathematics module.

This is because in your first year with the OU you have to take 3 maths modules and one generic module (all of which are crap). So i am going to fill the 30 credits this way. [This is sort of irrelevant]

I really had fun with Chem in College and didn't want to take it in University, but now i have the opportunity to do so, Its swaying me back to the OU.

The possible things i'd like to do after uni are:

1.Become an Actuary.

2.Masters in Mechanical Engineering. (Apparently its possible, thus the chem)

3.Postgrad, masters/Phd. (In a numerical science)

I like the sound of Computational Physics.

4.Programming.

Now, for my question to you.

Given these two options, ignoring cost, which would be the better option? for me? for you even? I am open to opinions/suggestions, I am sort of on the fence here.