I like top better.
For me an $11 Vivi Nova with an aluminum tank and 3 heads in the box is tough to beat.
Out of the box they're OK, so I go ahead and use them, but I do rewind them with better wicks (for my taste) tho', and the Vivi Nova is super easy to re-wind. The rebuilt ones are NICE, and the learning curve to get there was surprisingly low.
I like the coils being closer...the fire is almost right at the end of the drip tip. More warmth at lower coil temperatures, and to me it feels more like the best drags on a real cig or cigar.
I sense a slight cost in flavor and throat hit off a top coil with some liquids, but it's nothing I cant fix with the liquid mix next time I order or make it.
Both are really good these days.
Best to get some of each and enjoy both. Alot of it may depend on the liquid you're using...some will be better in the top coils, some better in the bottom (and that will, of course, be SUBJECTIVE to personal taste).