Canisters are not exactly better than say a hang on top(HOB). Canisters have their pros and cons. Pros: they are cleaner profile since they can be hidden and allow the tank to be closer against a wall; hold more media. Cons: much more effort to clean out; more leakag/flooding potential.
For a 45, I would recommend you just keep things simple and go with two AquaClear70 HOBs. Its more beneficial to run multiple smaller filters than one large single unit. If you're still set on using a canister, then I recommend then Sunsun HW302. It's rated for a 75gal, so in actuality will be perfect for a 45gal, and it'll cost you less than $50. I actually own this particular model and 2 of their largest modells, so I know they work just fine.
But, as already stated, mechanical filtration units does not replace water changes. Aim for 50% weekly at the very minimum, but more is better