I am a horrible skateboarder. I always wanted to learn as a kid but never did. I cant even "regular skate" down the street very well... yet I can surf, wakeboard, snowboard, etc... Its the kicking that throws me off. so a electric board works fine for me. I step on and pull the trigger, it starts moving and Im fine... except I cant stop well.
Good Production boards for the most part.. just work. no belt mis-alignments. no fiddling. etc... but they're slow. As much as I prefer building things, a used boosted board is the direction I went for regular "keep in the car" use. I cant go fast, because I suck at riding. lol.
DIY custom boards will be more of what you want... deck style, truck width, wheelsize, battery capacity, speed and torque.. all exactly what you buy.... However you usually buy better quality items so the cost is a wash. Depending on how you do your motors, you might have belt issues initially. (they're finicky to setup) You can build one dead reliable, but it takes time.
Because the cost is a wash, if you have never ridden an eboard before or are new to skateboarding, I would buy a used electric board first... then if you like it you can get a better idea of what you want. For me, I found that the board is good for when I park a mile from where I need to go downtown... but when I am out for some electric fun, I prefer the bike or scooter. they both go 40+mph, turn and stop much better. As cool as skateboards are, they're more for me to watch than do.