I'm considering Marsa Alam for several reasons - rental guarantee, position - seems like it could be good for future, & buying on a 5 star resort. Yes you can buy in Hurghada for similar price, but they are basically apts with pool access, as far as I can tell. This will be a resort in itself with lots of facilities & hotel renting out on your behalf. Seems to me renting out in Hurghada will be well nigh impossible with hotel deals & number of apt blocks available.
Like I say, I'm no expert & stand to be corrected..... but thats my take on it at present.