I use MRC B&W filters, mine normally cost around $70-80, but I typically get 77mm filters which are more expensive than smaller filters.
I would say it depends on your lens. If it's an L series or professional grade lens, then a B&W MRC filter is my choice, I have them on all my lenses. If you have a lens worth less than $500, you may consider hoya brand.
as for the rain sleves from Opto, love them. I have them in my bag and on my ThinkTank belt at ALL times! It's such cheap insurance!
I looked up the B+W MRC and I'm not sure what advantage the multi-resistant coating has over the less expensive B+W UV filter I was looking at.
The lens I'll be using is the Zuiko 12-60mm with an MSRP of $999. It's really an excellent lens and I want to be sure that anything I put on it will not degrade the quality of the photos.
Right now I have the B+W MRC in my cart, but I want to understand why I have to pay $20 more for this filter rather than the other one.
Thanks!