If you go hub motor, do rear wheel, It just avoids any problems with the fork breaking on you. It will probably mean you can't re-use your cassette, but I'd pay $30 for a freewheel vs having to worry about going over the bars.

The BBS02 mid drive will cost more, but is a lot easier to wire up than most inexpensive kits. It's just a matter of placing the battery and putting the display, throttle and brake levers on the handlebars. And then you can re-use the whole rear wheel/cassette.

If it is a racing style bike with dropped bars, you're going to have to think about how you want the controls. Kits are mainly designed for flat handlebars.