Simple answer is atrs modern sporter if you still have testicles. Cz bren if you have money to burn, still a very nice rifle
I would ignore the questionable advice above. The ATRS Modern Sporter arguably offers the best fit and finish of the available options, however the firearm is not currently in production and has a hazy legal status based on its RCMP inclusion in the FRT Prohibitions as an "AR15 Variant". This latter point is the most salient, given that Modern Sporter owners who wish to discharge their rifle must defy the RCMP's current classification and risk seizure and charges of unlawful possession of a "Prohibited Firearm". Ignoring extant law may demonstrate "testicles" in the eyes of certain individuals, however it may very well also land you in very hot water. Not a good look right now from a legal perspective.
In light of the above, I share "Belt-fed's" opinion that the Lockhart Raven 556 is currently the best NR 5.56mm rifle on the Canadian market. This internal-piston design is as close as you are going to get to an AR15 style of rifle in Canada with a NR FRT. The Raven Platinum edition features fully ambidextrous AR15-type controls, strong reliability based on an adjustable Gas Block, soft recoil, predictable and consistent ejection, comparatively light weight and just about every other positive characteristic of the AR15 type rifle. The Fit and Finish are Excellent throughout, easily on par with the Sterling Arms International R18 Mk1. Accuracy is very satisfactory, averaging an honest and realistic 2.5 MOA with bulk PMC Bronze ammo in 5-round groups from 100m. Hornady Match ammo in particular gives superior accuracy results right around 1 MOA if you can afford the expensive fodder. Speaking of cost, the price on the Raven varies by the rifle edition that one selects. The top of the line "Platinum" edition featuring full ambidextrous controls and selected add-on options such as the Top Charging Handle, Casing Deflector and Left Side Cocking Slot Cover will set you back approximately $3300.
There are numerous contenders for "second place" on the current Canadian market, however they all feature one or more dubious characteristics worthy of cautious consideration. In the case of the much-touted CZ Bren 2, the problem lies in the fact that there are currently no factory rifles available with 18.5" Factory, Cold-Hammer-Forged and chrome-lined barrels. As a result, the only available NR examples have been fitted with Button-rifled, non-chrome-lined aftermarket barrels of indeterminate pedigree. Some, touted as being "Match" grade have been turning in 4 MOA groups at 100m with 55gr service ammo! That sort of performance from re-barreled Bren 2s ought to make anyone leery about purchasing an aftermarket rifle with no factory Warranty for $4500(+). I have one, but mine is in the Restricted class with a factory 14" CHF and chrome-lined Barrel which produces 2.5 MOA accuracy with bulk 55gr PMC Bronze ammo. I have no complaints about the factory rifles, but the re-barreled, NR examples are unfortunately a very expensive crap-shoot in the accuracy department.
There is also the Tavor X95 for those who prefer (or can abide) a bullpup configuration. It is mil-spec in most regards, with the reliability and durability that the term implies. Mine prints 3 MOA, 5-round groups with bulk 55gr PMC Bronze from 100m with a Cold Hammer-Forged and chrome-lined barrel. The ergonomics are somewhat awkward with a fixed Length Of Pull, but the X95 is not bad if you can adjust to its "fit". The price is competitive at $2700, however the X95 appears to be largely sold out with no indications of a re-stock inbound.
The B+T APC 223 has the distinction of being the most expensive of the semi-auto, centerfire rifles still currently available to Canadians at a cost of approximately $5K. It is a superbly-crafted piece of Swiss engineering with outstanding fit and finish. Accuracy is good at approximately 2 MOA with bulk 55gr PMC Bronze ammo and reliability is excellent. The APC 223 is an excellent choice where money is no object and one simply has to have the very best available.
The FAMAE SG540 is another conventionally laid-out sporting rifle, this time based on the Long-Stroke Gas Operating system. Mine is an excellent performer, albeit with somewhat dated features such as a fixed Length of Pull in both the factory fixed and folding Buttstock versions. Ergonomics are somewhat limited, but the controls fall easily to hand in terms of the Selector Switch, Bolt Catch and ambi Magazine Release. My SG540 prints approximately 2 MOA 5-round groups at 100m using bulk, 55gr PMC Bronze ammo with excellent reliability. The FAMAE rifles can be easily fitted with a Receiver Extension/Adapter for the Magpul Yugo-variant "Zhukov" Folding Buttstock with an adjustable Length of Pull if that is an issue with the factory Buttstocks. New FAMAE SG540 rifles are currently available in the "Flat-Top" variant without iron sights for approximately $3600. The better option is the Iron-Sighted variant with the "classic" furniture, assuming that you can locate one used. Note that the newest variant, the SG 540M with a Polymer Buttstock and Picatinny Handguard should be avoided. The Buttstock is both uncomfortable and flimsy and the Picatinny Handguard is excessively heavy and rough on the hands.
As far as the AR180B-derivative rifles are concerned, Canadian buyers have several decent design choices. The R18 Mk 2 exhibits the best fit and finish of the pack, with good accuracy, strong reliability and satisfactory durability (albeit somewhat heavy) at a price of $2700. The Crusader Arms Templar Gen 2 is another viable option with very good fit and finish, decent accuracy, excellent reliability and superior durability (but again, Heavy) at a price of $2250. I personally do not recommend either the WK180 Gen 1 or 2 or the WS-MCR, although the latter is a decently-performing rifle hampered by poor ergonomics and excessive weight.
Everything else semi-auto and centerfire that is still available to Canadian shooters can only be had in Used Condition because production or importation has long since ceased. The Bushmaster ACR and the HK G36 both immediately spring to mind. Each has their strengths and weaknesses, but suffice it to say that both are excellent sporting rifles. They are reliable, durable, reasonably accurate, and still available on the CGN EE or ####### if one is patient enough to wait for the right used example to come along. The biggest down-side of these used firearms is their price. The used Bushmaster ACRs typically sell for $4500 and up, whereas a G36 "Parts Gun" built on all-German parts will run you a cool $10K. Another option which I have no personal experience with is the Norinco Type 97 Gen 3. They are apparently reasonably accurate and reliable now that the feed-geometry issues have been resolved. The price for a little-used unit tends to sit around $1500 these days, making it one of the more budget-oriented options remaining on the Canadian market.