Some companies have policies on credit cards for expenses but if its your own it shouldn’t make much of a difference. People ran into problems when they started picking things based on the points value to them rather than the cost to the company.
Amex is not widely accepted, if it is going to be your only card then you may struggle. Some do offer joint ones. I think our Natwest is Visa and Mastercard.
FWIW our main credit card is a flybe since we get free flights to Jersey (to visit family). We put everything through the credit card and get 2 return flights each a year. With putting a lot of wedding expenses through the card we are probably going to be able to do a long weekend in Europe as well this year.
If we didn’t have a flybe I’d probably get a nectar/sainsburys one. We do most of our shopping there and buy petrol so already have plenty of points so this would be enough to make a meaningful saving.
Cash back ones all seemed limited to 12months at any decent rate. You seem to get better value with the more specific points ones but this is only worth it if the points are useful to you.