what motor you decide on is dependent on how you drive, what other mods you are going to do to your car, and your goals. the b18b is only 140 hp, and is definitely not the motor you want to run if your going to stay n/a. if you do this swap, you definitely are going to want to turbo it too. this is probably the best stock b series motor to turbo thanks to its lower compression ratio. correct tuning can allow you to run 12 psi on it, which can equal almost 300 wheel hp. this is by far the cheapest swap, as you can find these motors in local junkyards. they are also easy to get parts for because honda build far more b18b's in the us than it ever did b16's or b18c's. stock they make more torque at a lower rpm than either the b16 or b18c, so if low end grunt is what your looking for, this is a good motor to start with. 142 hp, 127lb/ft
the b16a has similar hp to the b18c, but it has less torque. its best feature is its almost perfect 1.75:1 rod stroke ratio, which allows it to safely rev to 9500-10,000 rpm's. all this motors power is concentrated high in the rev range, so be prepared to do a lot of shifting to keep the engine well into vtec. there is a reason that this engine is almost a grand cheaper than a comparable b18c, the extra 25 lb/ft of torque in the b18c makes a world of difference, especially around town. 170hp (160 usdm) 111lb/ft
b18c is the best (affordable) b series motor. the b18c5 (type r) motor makes more hp, but its $5000+ pricetag is just out of this world. you should be able to find this motor for around 3 grand or so. stock it is faster and torquier than the b16 thanks to its extra displacement, and mods are also more effective on it. if you plan to do only bolt ons and leave the motor pretty much stock, this is the engine to get.
all these motors will go into your car with a mount kit from hasport or another engine mount company. the wiring changes needed depend on the year of the motor and what wiring cutting was done when the motor was removed from the car. the easiest motor to swap in would be a b16a2 from a 99-00 si, which if you get the full package from the car, should bolt in and plug into your car. otherwise, there will be some wiring mods needed to your car. if you get a vtec motor, you will need to run a wire for the knock sensor, and i believe some of the emissions equipment wiring is different and will need to be modified. i know some companies make wiring harness for this swap, im pretty sure place racing does, which can make it easier.