ACST.com > Lovo.com > DBHJ.com > Qlek.com > Qloy.com > XHBQ.com
The chances of finding a business with the letters ACST is very very good - those are the 4 most commonly used letters. LOVO is a true pronouncable, but it must compete with all the other pronouncables, and to some extent the 5 and 6 letter pronouncables. It is very close to "love" so many businesses whose product is not related to love will avoid it and those who are related may be concerned with losing traffic to Love.com.
I have many domains like DBHJ.com, 3 nice letters and one not-so-nice. The J is the weak point. Still a good chance of an end-user: Journal (great at the end) Jones and Johnson. Without doing the math DBHJ would rank, I would guess, in the upper half of LLLL's for better letters.
Here is where I diverge from the crowd. The largest percentage of the remaining unregistered domains have "Q"'s. That means that "Q" is the least popular, most difficult to find an end user for, of all the letters. Would someone want to name their new business, their big dream, QLOY or QLEK ??? I don't see it. They would choose an anagram that has meaning to their business, they would choose a true pronouncable with 5 or 6 letters that they could afford, or even a descriptive two or three word domain.
A lot of people disagree with me here, and at this time QLOY.com might sell for more than DBHJ.com. Time will tell.