okay as somebody who went through this debate...let me answer your concerns...
->1-good life style with work load of around 50 -70 hrs
uh, generally 70 hours is usually not considered a good lifestyle
most allergists don't work this many hours...they are mostly 9-5 (many are 4 days a week), most don't have much in the way of call and if so its not demanding...
heme onc will vary according to the practice you join....a larger group would mean better distribution of work etc. heme onc can be back breaking to very family friendly but it depends on the practice you choose...
->2- financially rewarding
salaries in allergy range but usually people start in the late 180-200s and can potentially cap out at 400 depending on the practice you join...
heme onc start out higher and has the potential to make more than allergy (because of chemo etc) but it depends on how much work you want to put in.
->3-good job prospect after fellowship
job market is definitely better for heme-onc...more job options in major areas...allergy is a tougher market but job forecasts in allergy are expecting a shortage in the next few years...
->4- which is easy to get
both are relatively competitive...however allergy may be a tad harder due to the less number of spots...and the fact that medicine applicants will sometimes be competing with peds for the same spots...
5- future of these fellowships???
they are both great fields...really this is the way you have to look at it...
most heme-onc guys do both hematology and oncology. definately a much more demanding patient population but definately very rewarding. you can be very in heme-onc and your emergencies can be more life threatening.
allergy/imm...if you really like immuno, most priv. practice guys will not be doing pure immuno unless you choose to go academic. most of allergists will see a lot of asthma, allergy, food allergy and rhinitis/sinusitis...you have to like these diagnoses...also the amount of immuno you learn varies depending on where you do fellowship.
i would definately do a lot of electives as students and residents for both areas of specialty and try to decide where you see yourself...also research is definately recommended for both prior to applying for fellowship...
i decided on allergy/imm and i'm really happy with my decision but i think heme-onc would have been good too...
good luck.