It really depends on which are your purposes. 99% of the tiem remarketing campaigns are pointing to direct response goals. In that sense it may be best to use CPC bidding to better calculate your ROI.
If your remarketing campaign are for branding purposes then a CPM may be the best way to be sure your ad is getting the highest exposure possible.
I think that CPC is the best model in terms of ROI calculations, just depends if you have catchy banners with your phone/branded so you want them to be shown as much as possible or if you have text links pointing to your best converting page.
Moreover. I remember that google translates CPC bids into eCPM ones when competing which means that if your CTR is really low you may risk of paying even more than by bidding with CPM. I can't reckon the exact formula, maybe someone can help here, but I remember that if your CTR is lower than 0,10% you may consider CPM since you're paying much less for 1 click than for a thousand impressions. (need more insight on this)