I personally own 6 Mosins, an M1891, 2 91/30s, an M38, M44 and 91/30 PU. I also own a1942 Longbranch No4. I will take ANY of my mosins any day over the Enfield. Personally, I can work a Mosin bolt faster, load via stripper clips faster, take up a sight picture a lot quicker, and I find I am more accurate with any of my Mosins (handloads). The Enfield isnt a bad rifle, but can be plagued with many finicky problems I find. Such things as the shrinkage of the stock and bedding of the stock. I found with my No4 if these things arent perfect, you wont hit anything. Whereas Mosins will take a beating, and still mainting a very respectable level of accuracy. They are a very robust rifle, capable of much abuse before worry.
Ammo - The 7.62x54R is a great cartridge all round, my personal favourite. With reloads you can start as low as 125gr and move up to 200gr with no issues. I have found a 150gr .312 bullet with 48 gr of RL15 will produce outstanding results accuracy wise. The 54R generates a lot of power and can be used quite easily past 500m +. The .303 is also another combat proven round but I find the 7.62x54r to be more accurate (Im going to get flamed for this!) I have fired quite a few Enfields, I just like the 54R better. Both will cost about the same to reload, and surplus for both rifles is currently few and far between. Factory ammo is about the same price wise, but with the .303 being more common.
Sights - I find the iron sights on the Mosins a lot better then the Enfields. The Mosins ''point' a lot easier then the Enfields, and line up a lot faster then the No4 post and aperature. I find that lining up the Enfields sights in low light can be a pain. Again your experiences will vary.
Workmanship - WW2 era Mosins will be roughly finished, but will function reliably with no issues. The pre and post war Mosins have very nice finishes and are very smooth.The No4 rifles have nicer blueing, typically nicer stocks, better triggers and smoother metal. However, to me my Mosins feel "tougher", I find my No4 stock scratches really easy, while my Mosin stock dosnt. The Enfield is very 'refined', and is a very slick rifle, I just find the Mosin more of a 'working' rifle.
Bolt - Everybody seems to love the No4 bolt and hate the Mosins awkward stubby bolt. I find the No4 to have a nice bolt, but the spring tension needed to close the bolt is annoying to me. With the Mosin, using the palm of your hand, the bolt will open and close fairly easily. I find that I can work a Mosin much faster then any Enfield bolt, and more reliable (I have had a few Enfields that wont chamber the last round in the mag, never a problem with any Mosin).
Accuracy - Mosins and Enfields both have the potential for very good accuracy. One thing I find is most people who complain about "junk accuracy" out of a Mosin are using surplus ammo. As much as I love surplus ammo, it isnt as accurate as reloads or factory stuff, and rightfully so, its mass produced military grade stuff. With handloads I have been able to do a HAIR under 1inch at 100m with 2 of my Mosins, with the rest in the 2ish inch area. With surplus this can EASILY double, if not triple. With the Enfields, since most people are firing newer ammo, or factory, they find that they are more accurate, and rightfully so they will be. With old surplus you can expect the same results as the Mosins. Of course bore condition is everything, the best ammo and the worst bore will produce poor results, as will the best bore and worst ammo!
Overall I find the Mosins a better choice. The Enfield has its advantages such as a 10rd mag, nicer looks (if that matters to you), easy availability of ammo and a nicer trigger/overall feel. However, the Mosins I feel are underappreciated and are a very capable rifle, and with the prices what they are, I feel a MUCH better deal then any Enfield!
Oh, and yes, I AM a Canadian! not a Russian