The whole H22A in a civic is a myth, It's only 85 lbs heavier than a b16a, and with any decent suspension work you will NOT notice the weight difference. It is a hard swap, but well worth it IMO. It will put an otherwise stock EG hatch into mid 13's in the 1/4.
B20 is fairly expensive, everyone says its not, everything is nickel and dime stuff, after you buy the motor, you have to buy tranny, ecu, mounts, intake manifold, exhaust manifold, fuel rail, injectors, linkage, not to mention all your gaskets etc, and lots more little things, it will cost you way more than you think.
B18C5 is a sweet motor, but over rated IMO, unless your getting a wicked deal on it, your better off with a B18C1 and modding it for the same price. Plus the C5 has high compression which is bad if your gonna go the turbo route
B16A2 would be your best option if you want cheap and easy, if you want some fun and a little work, but good power, go H22A