I would say there is no "better". The two systems are fundamentally different.
DC systems are mainly preferred for reasons of cost, or performance. If you are on a budget or want 1000A, tire-spinning performance, you generally have to use a DC system.
If you want regenerative braking and more efficient use of the power, you generally have to use an AC system. Let me also say that generally, regen is only going to add 5% to the range; it is not the regen that accounts for the majority of the extra range, it is the increased efficiency. Where the regen is really helpful is with it's braking effect.
The AC systems begin at about $8000, which is a little more than double what DC systems begin at. A really nice DC system, with a WarP 11" motor and Zilla 2K would not even cost $8000, and the AC systems that cost that much are low performance models. The really nice, high end AC systems that places like Metric Mind sell will begin at over $10K, easily. They are nice if you can afford them, but once you go into that territory, it would be downright cheap not to couple it with a premium battery pack, and then you are into the 50K range. If you can afford to go there, you will be able to make a very nice, showpiece conversion.
There is a reason that many DC conversions are being completed every day. They make an excellent cost effective electric vehicle for most people, and are probably the only type of conversion that will actually pay for itself if the costs are compared.