Depends on what you mean by 'easier', do you mean in terms of sponsoring him for his residency in Canada? As far as I know, it shouldn't matter one way or the other where you marry for sponsorship reasons.
However, if you decide to marry in the UK and you have a civil ceremony (at the local Town Hall), you will need to get 'permission' from the UK government. You need a Ceritificate of Approval, look here
http://www.ukba.homeoffice.gov.uk/visitingtheuk/gettingmarried/certificateofapproval/. Before that though, you need to have entered the UK on fiance or marriage visitor entry clearance, not just as a tourist (this is all assuming one of you is not a UK citizen). The COA can take up to 3 months to process, then once you get it, you have to give your notice of marriage and wait at least 2 weeks after that to have your ceremony.
All of this can be avoided if you marry at a CofE (Anglican church). In the UK, you get your marriage certificate straight away (as in, on your wedding day), in Canada, I have heard that you have to wait a few months for it (I could be wrong though, I was married in the UK).