Well Judo is defo easier to get a black belt in. I don't think anyone would dispute that. I would say on average it takes about 700-1000 hours to achieve it. This number varies according to athleticism, size and quality of instruction. Since there is a competitive requirement whereby you must win 10 fights by Ippon against brown or black belts in competition. Alternatively you can win 5 fights in one day (including 3 in a row with no breaks in between) at a grading which is usually openweight although they try to match you with people your own size as much as possible. This is called a line up and is the preferred method of achieving the black. Heavier guys will find it easier to do it this way since they are less likely to be overpowered.
I did it in about 200 of the highest quality training with international level players, former olympians etc, but that obviously doesn't include all the time I spent thinking about techniques, shadow uchi komi (shadow boxing for judo players), looking up youtube instructionals, watching international Judo, talking to my flat mates about it, documenting my progress etc. I really threw myself into the whole scene as much as possible and got my black belt in just under 2 years. I did it through the 10 wins over a period of a few weeks method since Im not a particularly big gut although I did just miss out on my line up once (won my first two, got to my 3 in a row, won the first 2 by ippon but only won the last one by waza ari, a smaller score, so it didnt count. Before anyone says it is an IJF accredited black belt and not a mcdojo black belt, which includes a competitive requirement as well as a technical requirement to achieve. I am currently targeting national trial qualification within the next 18 months. If my remaining competitions go well this year I could make it in January although I think this is a little ambitious