i know a few people who drive rally and rallycross, and i've went to see some events, and if i were to do some sort of motorsports, it would definately be rallycross
compared to rally the tracks are shorter and windier, so it's more to driving skill and you don't realy need a fast expensive car, entrance prices to compete are a lot cheaper as well
and it's simpler, it's just drive your heat, and go watch the others (or repair your car). in rally you're constant under stress caus you have to reach the next checkpoint on time.
and since all the action takes places on 500m?, it's nicer to go watch as spectator as well, you see everything, whereas in rally you only see 1 bend at the time