LOL I don't know which is more amusing, getting asked this question on a long forgotten thread on a low traffic message board, or the fact that Jim actually jumped in with an answer less than two hours later.
So yes buy them all. Actually, buy multiple copies of them all, they make great stocking stuffers!
But if you're on a tight budget in our troubled economic times
Gosh it's been a while since I've seen these now. The first four in my list are so similar that I'd almost recommend choosing based on the cast lists. If you want something different,
Lust Connection
is definitely the most unique of these five, sharing locations and other similarities with the other films, but being a serious thriller with a pretty good plot whereas the other films are all silly supernatural comedies. And if you're a big Glori-Anne Gilbert fan, then that film might be a good choice because she plays dual roles and gets the lion's share of the screen time.
If you put a gun to my head and made me choose, I'd probably take the two
Witches of Breastwick
flicks. I enjoyed them both even though the 2nd one is essentially a remake of the 1st, as opposed to a sequel.
Enjoy your choices
That's part of your problem, you haven't seen enough movies. All of life's riddles are answered in the movies.

Personally, I'd buy 'em allbut that's just me(Jim Wynorski) talkin'

If I had to choose and buy two of those on dvd, which ones would you recommend?

Well during the closing credits of his most recent film to hit late night cable (
The Da Vinci Coed
) one of the cast said that the next project was
House on Hooter Hill 2
. I shall expect more of the same continuity.
That's part of your problem, you haven't seen enough movies. All of life's riddles are answered in the movies.

It's all part of his Zappa-esque conceptual continuity!

And if you had watched more than just the first 5 minutes, you would have noticed a lot more similarities
In fact, I've seen the following 5 films in pieces or total, and they are essentially the same film
The Witches of Breastwick
The Witches of Breastwick 2
The Breastford Wives
The House on Hooter Hill
Lust Connection
Similarities seen in 3-5 of these films

• married couple drive same car up same mountain road, pull cb68ar over in same spot, and have sex on blanket in the woods
• married couple arrives at same house with same bathtub/hot tub/bedroom/deck/etc.
• house always occupied by 3 or 4 big chested women
• one male lead (husband) and a boatload of female characters
• husband has one-on-one sex scene with every (or almost every) female
• wife has two all-female threesomes, one in hot tub and one in the bathtub
• always one sex scene where husband has sex with another woman on the same couch in the bedroom entrance while his wife in the bed fails to wake up for some reason
• always one outdoor sex scene (in addition to the mountain roadside scene mentioned above)
• always a mystery woman shows up out of nowhere (husband always bangs her too)
• all or almost every female is a "breast queen" (that may be a requirement when the title includes "breast" or "hooter")
• two of the films have a woman strangled in the hot tub early in the film
  That's part of your problem, you haven't seen enough movies. All of life's riddles are answered in the movies.

I noticed that too.

yeah I notice the same thing
"I wanted to test the bounds of reality, thats it I swear"