Well NaN was kind enough to link my thread which I had forgotten about (and I need to edit I see LOL) but it should get you off to a good start.
I personally find growing from seed to be very rewarding but it takes a
lot of patience. Do not be surprised if it takes years to get germination. And be ready to trip up along the way cause yearling tubers are tiny and sensitive to too dry and too wet. But if you are willing to put in the effort then it is a great reward.
Now as for the species you asked about:
D. erythrogyne
Have not tried this from seed yet. Since it is related (at least peripherally) to macrantha I suspect it should not be a great challenge but I do not expect it to be "easy"
D. gigantea
This has been an easy one for me. Germination usually happens first year and if not definitely the second year. Do not expect monstrous plants for many many years though.
D. macrantha
THis is another species I have always had good luck with. Germination usually occurs by the second season. These plants start very small and will often stay rosetted their first year or two.
D. stolonifera (rumored to be among the easiest?)
Easiest how? To grow or to germinate? I would say neither is true. If you put an addendum on it I will concede it is one of the easiest of the fan leaf tuberous but it still takes a bit more diligence than things like peltata and the like. As for germination, this is one of the ones that can take 3-5 or more years to germinate so be ready for a wait
D. zigzagia
I have not grown this one from seed but know someone who did, got blooming plants in a little over a year so I would say this is a good candidate. My plants form TC are super easy (and blooming again this year, right now actually.)
D. huegelii
Never grown this one so I can not offer anything on this one
D. subhurtella
Another I have not grown but I have grown the related moorei and it proved easy enough though it was not from seed. I imagine this would fall in the same general area as the macrantha types so be prepared for germination in the first couple seasons but be willing to wait longer.
D. cistiflora (Not quite tuberous, but close)
Been playing with these for a few years. My experience is that the seed needs a full cycle to get the best germination though you will probably get some straight off it you keep the pot permanently wet.
D. peltata (Also said to be easy?)
This is a very easy species. Seed will germinate where ever they fall, often without even having a dry cycle. Can be up to blooming in a single season though usually it takes 2. This is your best bet as a beginner.
I posted some seedling shots here a bit ago but here they are again
Various tuberous
D. cistiflora